diff --git a/Framework/API/inc/MantidAPI/ADSValidator.h b/Framework/API/inc/MantidAPI/ADSValidator.h
index 5efc517329bbb70606a24c57bb8d6dc7c547eaab..b43de86d127bb94c97963b2e0b408b32d3b2dbe9 100644
--- a/Framework/API/inc/MantidAPI/ADSValidator.h
+++ b/Framework/API/inc/MantidAPI/ADSValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ADSVALIDATOR_H_
-#define MANTID_API_ADSVALIDATOR_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -59,4 +58,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_ADSVALIDATOR_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/AlgoTimeRegister.h b/Framework/API/inc/MantidAPI/AlgoTimeRegister.h
index 3f5c1cb7fe10bf5a4d554ee54944b917342821d2..f9b8a61b2a393526b6c221cf61b9672137008b4a 100644
--- a/Framework/API/inc/MantidAPI/AlgoTimeRegister.h
+++ b/Framework/API/inc/MantidAPI/AlgoTimeRegister.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGOTIMEREGISTER_H_
-#define MANTID_API_ALGOTIMEREGISTER_H_
+#pragma once
 
 #include <mutex>
 #include <thread>
@@ -59,4 +58,3 @@ private:
 } // namespace Instrumentation
 } // namespace Mantid
 
-#endif /* MANTID_API_ALGOTIMEREGISTER_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/Algorithm.h b/Framework/API/inc/MantidAPI/Algorithm.h
index c3b3ced81dedf8699ada52e2358830489928bbbc..17d4d845118b7485481a88e189c7ff300676dafd 100644
--- a/Framework/API/inc/MantidAPI/Algorithm.h
+++ b/Framework/API/inc/MantidAPI/Algorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHM_H_
-#define MANTID_API_ALGORITHM_H_
+#pragma once
 
 #include <atomic>
 
@@ -522,4 +521,3 @@ using Algorithm_sptr = boost::shared_ptr<Algorithm>;
       (Mantid::API::AlgorithmFactory::Instance().subscribe<classname>()), 0)); \
   }
 
-#endif /*MANTID_API_ALGORITHM_H_*/
diff --git a/Framework/API/inc/MantidAPI/AlgorithmFactory.h b/Framework/API/inc/MantidAPI/AlgorithmFactory.h
index 0ad9508293e6426895f5e0a956f2c8ac0b3bc423..6acaecb013398307a3ce22e970ed1c892d36d26e 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmFactory.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMFACTORY_H_
-#define MANTID_API_ALGORITHMFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -171,4 +170,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /*MANTID_API_ALGORITHMFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/AlgorithmFactoryObserver.h b/Framework/API/inc/MantidAPI/AlgorithmFactoryObserver.h
index 29329b35c6e0109f7e7e2d03ef2464e06ff12b40..0e30e1a3f0eb2a21f0476778fad31e37ca5013a8 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmFactoryObserver.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmFactoryObserver.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_KERNEL_ALGORITHMFACTORYOBSERVER_H_
-#define MANTID_KERNEL_ALGORITHMFACTORYOBSERVER_H_
+#pragma once
 
 #include "MantidAPI/AlgorithmFactory.h"
 #include <Poco/NObserver.h>
@@ -53,4 +52,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_KERNEL_ALGORITHMFACTORYOBSERVER_H_*/
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/AlgorithmHasProperty.h b/Framework/API/inc/MantidAPI/AlgorithmHasProperty.h
index 44b6661db2eb4574c6ae8bd639d1db79506317ab..c786842d2f0de5d2c56eda98910f05b1387310ec 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmHasProperty.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmHasProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMHASPROPERTY_H_
-#define MANTID_API_ALGORITHMHASPROPERTY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/TypedValidator.h"
@@ -41,4 +40,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_ALGORITHMHASPROPERTY_H_ */
diff --git a/Framework/API/inc/MantidAPI/AlgorithmHistory.h b/Framework/API/inc/MantidAPI/AlgorithmHistory.h
index 59f63f111216a0b39aebb39d3384b48d3908dec0..1cf5325acc50aa2bc63260d04f728a73ca1179d3 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmHistory.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmHistory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMHISTORY_H_
-#define MANTID_API_ALGORITHMHISTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -152,4 +151,3 @@ MANTID_API_DLL std::ostream &operator<<(std::ostream &,
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ALGORITHMHISTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/AlgorithmManager.h b/Framework/API/inc/MantidAPI/AlgorithmManager.h
index eb892ae5f1e2e5358e98b24a663b92873a7bc1f4..a6fc251068df32e582df5cb6cfa211894972789a 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmManager.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmManager.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMMANAGER_H_
-#define MANTID_API_ALGORITHMMANAGER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -101,4 +100,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /* MANTID_API_ALGORITHMMANAGER_H_ */
diff --git a/Framework/API/inc/MantidAPI/AlgorithmObserver.h b/Framework/API/inc/MantidAPI/AlgorithmObserver.h
index aef65abb86b7d2d061ca7b9b60cb0e128b5582f2..c3a9c829b5483835a4383bb91248d5bc4b04c507 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmObserver.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmObserver.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMOBSERVER_H_
-#define MANTID_API_ALGORITHMOBSERVER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -76,4 +75,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ALGORITHMOBSERVER_H_*/
diff --git a/Framework/API/inc/MantidAPI/AlgorithmProperty.h b/Framework/API/inc/MantidAPI/AlgorithmProperty.h
index 6f3c8db8a0998e2ff86c463529d8f0252e85f082..90b4f956e0abd9b9e7988b2af446ceff2475bc3a 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmProperty.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMPROPERTY_H_
-#define MANTID_API_ALGORITHMPROPERTY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/NullValidator.h"
@@ -85,5 +84,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /* MANTID_API_ALGORITHMPROPERTY_H_ */
diff --git a/Framework/API/inc/MantidAPI/AlgorithmProxy.h b/Framework/API/inc/MantidAPI/AlgorithmProxy.h
index f756ba65064c10f3f5e63ff0e528b9d4da8d89e5..e3dceacb0907d51b494a20ca142a0798ec6c1309 100644
--- a/Framework/API/inc/MantidAPI/AlgorithmProxy.h
+++ b/Framework/API/inc/MantidAPI/AlgorithmProxy.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMPROXY_H_
-#define MANTID_API_ALGORITHMPROXY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -198,5 +197,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /*MANTID_API_ALGORITHMPROXY_H_*/
diff --git a/Framework/API/inc/MantidAPI/AnalysisDataService.h b/Framework/API/inc/MantidAPI/AnalysisDataService.h
index 126554a263eab78a3d2b379644696c748c5f9b1c..6df456a784471f12113a005534cf923330c730e2 100644
--- a/Framework/API/inc/MantidAPI/AnalysisDataService.h
+++ b/Framework/API/inc/MantidAPI/AnalysisDataService.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_KERNEL_ANALYSISDATASERVICE_H_
-#define MANTID_KERNEL_ANALYSISDATASERVICE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -231,4 +230,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /*MANTID_KERNEL_ANALYSISDATASERVICE_H_*/
diff --git a/Framework/API/inc/MantidAPI/AnalysisDataServiceObserver.h b/Framework/API/inc/MantidAPI/AnalysisDataServiceObserver.h
index 3445102cf040df86b47bd80f70a6ef12da118b8d..b7a05187b27bb9106f69c31368d1b9d91622a36c 100644
--- a/Framework/API/inc/MantidAPI/AnalysisDataServiceObserver.h
+++ b/Framework/API/inc/MantidAPI/AnalysisDataServiceObserver.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_KERNEL_ANALYSISDATASERVICEOBSERVER_H_
-#define MANTID_KERNEL_ANALYSISDATASERVICEOBSERVER_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/DllConfig.h"
@@ -137,4 +136,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_KERNEL_ANALYSISDATASERVICEOBSERVER_H_*/
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/ArchiveSearchFactory.h b/Framework/API/inc/MantidAPI/ArchiveSearchFactory.h
index d669139b0db838ac59eb612d83cc66d50c3d70d0..81d7cc6012c225c87c4d74aafaa47137fb2b5e60 100644
--- a/Framework/API/inc/MantidAPI/ArchiveSearchFactory.h
+++ b/Framework/API/inc/MantidAPI/ArchiveSearchFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ARCHIVESEARCHFACTORY_H_
-#define MANTID_API_ARCHIVESEARCHFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -53,4 +52,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif // MANTID_API_ARCHIVESEARCHFACTORY_H_
diff --git a/Framework/API/inc/MantidAPI/Axis.h b/Framework/API/inc/MantidAPI/Axis.h
index 4aeaf05bdea03dd9033890a7a11d96dee8421d8d..e48fc3a7c1db89b9c3024f4450943ff14e95ae38 100644
--- a/Framework/API/inc/MantidAPI/Axis.h
+++ b/Framework/API/inc/MantidAPI/Axis.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_AXIS_H_
-#define MANTID_API_AXIS_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidGeometry/IDTypes.h"
@@ -105,4 +104,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_AXIS_H_*/
diff --git a/Framework/API/inc/MantidAPI/BinEdgeAxis.h b/Framework/API/inc/MantidAPI/BinEdgeAxis.h
index e9e7bf4d0bb695d7c7d51a942df2b9829b756b5d..720a282565521705582f10f5d4d76702491ab010 100644
--- a/Framework/API/inc/MantidAPI/BinEdgeAxis.h
+++ b/Framework/API/inc/MantidAPI/BinEdgeAxis.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_BINEDGEAXIS_H_
-#define MANTID_API_BINEDGEAXIS_H_
+#pragma once
 
 #include "MantidAPI/NumericAxis.h"
 
@@ -39,4 +38,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_BINEDGEAXIS_H_ */
diff --git a/Framework/API/inc/MantidAPI/BoostOptionalToAlgorithmProperty.h b/Framework/API/inc/MantidAPI/BoostOptionalToAlgorithmProperty.h
index fd6bd104d331c94bda3f0f160f22d41a83ef118d..f304cf659db04fc25eed90ae9717d55b58cdad2c 100644
--- a/Framework/API/inc/MantidAPI/BoostOptionalToAlgorithmProperty.h
+++ b/Framework/API/inc/MantidAPI/BoostOptionalToAlgorithmProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_BOOSTOPTIONALTOALGORITHMPROPERTY_H_
-#define MANTID_API_BOOSTOPTIONALTOALGORITHMPROPERTY_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/DllConfig.h"
@@ -101,4 +100,3 @@ DLLExport boost::optional<std::string> checkForOptionalInstrumentDefault(
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_BOOSTOPTIONALTOALGORITHMPROPERTY_H_
diff --git a/Framework/API/inc/MantidAPI/BoxController.h b/Framework/API/inc/MantidAPI/BoxController.h
index 897f95d2dcaaf7e158b5fcb355c3536aa82e927e..6bb933877600f6b5ceadaed470f2e613d08177af 100644
--- a/Framework/API/inc/MantidAPI/BoxController.h
+++ b/Framework/API/inc/MantidAPI/BoxController.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef BOXCONTROLLER_H_
-#define BOXCONTROLLER_H_
+#pragma once
 
 #include "MantidAPI/IBoxControllerIO.h"
 #include "MantidKernel/DiskBuffer.h"
@@ -547,4 +546,3 @@ using BoxController_const_sptr = boost::shared_ptr<const BoxController>;
 
 } // namespace Mantid
 
-#endif /* SPLITCONTROLLER_H_ */
diff --git a/Framework/API/inc/MantidAPI/CatalogFactory.h b/Framework/API/inc/MantidAPI/CatalogFactory.h
index 6fed74f3a2f678ebd3506bca1318b95fc7e339ca..228fdb85349013176f0318dd5f967fc41da2f3ab 100644
--- a/Framework/API/inc/MantidAPI/CatalogFactory.h
+++ b/Framework/API/inc/MantidAPI/CatalogFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_CATALOGFACTORYIMPL_H_
-#define MANTID_API_CATALOGFACTORYIMPL_H_
+#pragma once
 
 /* Used to register Catalog classes into the factory. creates a global object in
  *an
@@ -76,4 +75,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /*MANTID_API_CATALOGFACTORYIMPL_H_*/
diff --git a/Framework/API/inc/MantidAPI/CatalogManager.h b/Framework/API/inc/MantidAPI/CatalogManager.h
index a228fdfb533509b605d34c737ab97fa7c3baaa9c..7c3ac54df97ea38e1d1d9056c0440118a3b183be 100644
--- a/Framework/API/inc/MantidAPI/CatalogManager.h
+++ b/Framework/API/inc/MantidAPI/CatalogManager.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_ICAT_CATALOGMANAGERIMPL_H_
-#define MANTID_ICAT_CATALOGMANAGERIMPL_H_
+#pragma once
 
 #include "MantidAPI/ICatalog.h"
 #include "MantidKernel/SingletonHolder.h"
@@ -63,4 +62,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
     Kernel::SingletonHolder<Mantid::API::CatalogManagerImpl>;
 }
 } // namespace Mantid
-#endif /* MANTID_ICAT_CATALOGMANAGERIMPL_H_ */
diff --git a/Framework/API/inc/MantidAPI/CatalogSession.h b/Framework/API/inc/MantidAPI/CatalogSession.h
index 22dd3290ff16169a6e7c4269204bfdcb5c274081..3769b48cc207a5a7a000283b9d8b0fa626573d48 100644
--- a/Framework/API/inc/MantidAPI/CatalogSession.h
+++ b/Framework/API/inc/MantidAPI/CatalogSession.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_CATALOGSESSION_H_
-#define MANTID_API_CATALOGSESSION_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "boost/shared_ptr.hpp"
@@ -40,4 +39,3 @@ using CatalogSession_const_sptr = boost::shared_ptr<const CatalogSession>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_CATALOGSESSION_H_ */
diff --git a/Framework/API/inc/MantidAPI/Citation.h b/Framework/API/inc/MantidAPI/Citation.h
index 24adcd509924c08eee58813c1b749bb8045e435f..8cec497d9a9bfd32159f8aed989f1ec7ff419922 100644
--- a/Framework/API/inc/MantidAPI/Citation.h
+++ b/Framework/API/inc/MantidAPI/Citation.h
@@ -5,8 +5,7 @@
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
 
-#ifndef MANTID_API_CITATION_CITATION_H_
-#define MANTID_API_CITATION_CITATION_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -74,4 +73,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_CITATION_CITATION_H_ */
diff --git a/Framework/API/inc/MantidAPI/Column.h b/Framework/API/inc/MantidAPI/Column.h
index 38c7518da2c82f0f6ebbd8b264ede7a43ddc15ce..d68488c46f335f9540a581f89a81c66ace2b6b07 100644
--- a/Framework/API/inc/MantidAPI/Column.h
+++ b/Framework/API/inc/MantidAPI/Column.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ICOLUMN_H_
-#define MANTID_API_ICOLUMN_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -238,4 +237,3 @@ using Column_const_sptr = boost::shared_ptr<const Column>;
 
 } // namespace API
 } // Namespace Mantid
-#endif /*MANTID_API_ICOLUMN_H_*/
diff --git a/Framework/API/inc/MantidAPI/ColumnFactory.h b/Framework/API/inc/MantidAPI/ColumnFactory.h
index ece4590f0572dda2338af19ae00052c221121424..34d77526b923a4becf0e2a016b13f15be7e38576 100644
--- a/Framework/API/inc/MantidAPI/ColumnFactory.h
+++ b/Framework/API/inc/MantidAPI/ColumnFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COLUMNFACTORY_H_
-#define MANTID_API_COLUMNFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -61,4 +60,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /*MANTID_API_COLUMNFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/CommonBinsValidator.h b/Framework/API/inc/MantidAPI/CommonBinsValidator.h
index 8f5197b033c4a7bb2c3477d719c1eb63c64a5c35..6a3fc1177a4ee0d59e3eac44a7137fa1bc8f6048 100644
--- a/Framework/API/inc/MantidAPI/CommonBinsValidator.h
+++ b/Framework/API/inc/MantidAPI/CommonBinsValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COMMONBINSVALIDATOR_H_
-#define MANTID_API_COMMONBINSVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -34,4 +33,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_COMMONBINSVALIDATOR_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/CompositeCatalog.h b/Framework/API/inc/MantidAPI/CompositeCatalog.h
index 749af14b134f0396102de431ee3675504f98b648..2fa199ba69b0610668b7609ce8a7fab35e66c1f1 100644
--- a/Framework/API/inc/MantidAPI/CompositeCatalog.h
+++ b/Framework/API/inc/MantidAPI/CompositeCatalog.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_ICAT_COMPOSITECATALOG_H_
-#define MANTID_ICAT_COMPOSITECATALOG_H_
+#pragma once
 
 #include "MantidAPI/ICatalog.h"
 
@@ -61,4 +60,3 @@ private:
 };
 } // namespace API
 } // namespace Mantid
-#endif /* MANTID_ICAT_COMPOSITECATALOG_H_ */
diff --git a/Framework/API/inc/MantidAPI/CompositeDomain.h b/Framework/API/inc/MantidAPI/CompositeDomain.h
index 5f98620438b8afb3e1c716797bf75ad9a4f99463..e85f12634f1c7a18fe9dcd1e37d6dbcf8bfc9d0c 100644
--- a/Framework/API/inc/MantidAPI/CompositeDomain.h
+++ b/Framework/API/inc/MantidAPI/CompositeDomain.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COMPOSITEDOMAIN_H_
-#define MANTID_API_COMPOSITEDOMAIN_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -34,4 +33,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_COMPOSITEDOMAIN_H_*/
diff --git a/Framework/API/inc/MantidAPI/CompositeDomainMD.h b/Framework/API/inc/MantidAPI/CompositeDomainMD.h
index 35bc9e4a08ddf11854d0db5aff8a89b5d399156e..54cfaa578d7b0d4e40c91a7a58d343dfff069d9f 100644
--- a/Framework/API/inc/MantidAPI/CompositeDomainMD.h
+++ b/Framework/API/inc/MantidAPI/CompositeDomainMD.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COMPOSITEDOMAINMD_H_
-#define MANTID_API_COMPOSITEDOMAINMD_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -47,4 +46,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_COMPOSITEDOMAINMD_H_*/
diff --git a/Framework/API/inc/MantidAPI/CompositeFunction.h b/Framework/API/inc/MantidAPI/CompositeFunction.h
index dc7b471752b6131389fa930f5225416c8f8ead51..457462de0346d99bbcffcc3c34a2f663648afe3e 100644
--- a/Framework/API/inc/MantidAPI/CompositeFunction.h
+++ b/Framework/API/inc/MantidAPI/CompositeFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COMPOSITEFUNCTION_H_
-#define MANTID_API_COMPOSITEFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -295,4 +294,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_COMPOSITEFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/ConstraintFactory.h b/Framework/API/inc/MantidAPI/ConstraintFactory.h
index 80d1e11a4d5eb5a056cc7cd3675b28193b2fa27d..1b6c641f238b2b58c36717c344a2787b6b9d864e 100644
--- a/Framework/API/inc/MantidAPI/ConstraintFactory.h
+++ b/Framework/API/inc/MantidAPI/ConstraintFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_CONSTRAINTFACTORY_H_
-#define MANTID_API_CONSTRAINTFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -83,4 +82,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
        0));                                                                    \
   }
 
-#endif /*MANTID_API_CONSTRAINTFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/CoordTransform.h b/Framework/API/inc/MantidAPI/CoordTransform.h
index 1018db380b4245a3ba90c587e186ea8072749503..f34ea0f79876f7743f14607a8326fed4eef32a85 100644
--- a/Framework/API/inc/MantidAPI/CoordTransform.h
+++ b/Framework/API/inc/MantidAPI/CoordTransform.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_MDEVENTS_COORDTRANSFORM_H_
-#define MANTID_MDEVENTS_COORDTRANSFORM_H_
+#pragma once
 
 #include "MantidAPI/SingleValueParameter.h"
 #include "MantidGeometry/MDGeometry/IMDDimension.h"
@@ -73,4 +72,3 @@ using CoordTransform_const_sptr = boost::shared_ptr<const CoordTransform>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_MDEVENTS_COORDTRANSFORM_H_ */
diff --git a/Framework/API/inc/MantidAPI/CostFunctionFactory.h b/Framework/API/inc/MantidAPI/CostFunctionFactory.h
index ca70621a7d5b1d16cb3b08bc72f6707ac580ef82..60d3ffb5cb3a94d0d2e7662fd5f6d2f019b377a6 100644
--- a/Framework/API/inc/MantidAPI/CostFunctionFactory.h
+++ b/Framework/API/inc/MantidAPI/CostFunctionFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COSTFUNCTIONFACTORY_H_
-#define MANTID_API_COSTFUNCTIONFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -62,4 +61,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /*MANTID_API_COSTFUNCTIONFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/DataProcessorAlgorithm.h b/Framework/API/inc/MantidAPI/DataProcessorAlgorithm.h
index 6a044b6b121dced0325c29e9835f9cef90e22cd5..80d537c761087000dd13eee759d7fafac9d42423 100644
--- a/Framework/API/inc/MantidAPI/DataProcessorAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/DataProcessorAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_DATAPROCESSORALGORITHM_H_
-#define MANTID_API_DATAPROCESSORALGORITHM_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/AlgorithmManager.h"
@@ -152,4 +151,3 @@ using DistributedDataProcessorAlgorithm =
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_DATAPROCESSORALGORITHM_H_ */
diff --git a/Framework/API/inc/MantidAPI/DeclareUserAlg.h b/Framework/API/inc/MantidAPI/DeclareUserAlg.h
index b811a4196e0aee87585156929c246af37d65f9bf..f5822bb9239f387dfa5c19d2103c7696a43f609e 100644
--- a/Framework/API/inc/MantidAPI/DeclareUserAlg.h
+++ b/Framework/API/inc/MantidAPI/DeclareUserAlg.h
@@ -4,12 +4,10 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef DECLAREUSERALG_H_
-#define DECLAREUSERALG_H_
+#pragma once
 
 #define DECLARE_USER_ALG(x)                                                    \
   Algorithm *x##_create() { return new x; }                                    \
                                                                                \
   void x##_destroy(Algorithm *p) { delete p; }
 
-#endif /*DECLAREUSERALG_H_*/
diff --git a/Framework/API/inc/MantidAPI/DeprecatedAlgorithm.h b/Framework/API/inc/MantidAPI/DeprecatedAlgorithm.h
index eb11179b7401f263a463f8ff45703684a20c2323..7cce8b71e510b4681af8e468f308cd4638901db2 100644
--- a/Framework/API/inc/MantidAPI/DeprecatedAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/DeprecatedAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef DEPRECATEDALGORITHM_H_
-#define DEPRECATEDALGORITHM_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/DllConfig.h"
@@ -43,4 +42,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* DEPRECATEDALGORITHM_H_ */
diff --git a/Framework/API/inc/MantidAPI/DetectorSearcher.h b/Framework/API/inc/MantidAPI/DetectorSearcher.h
index 7bde1a227adae7381492d9b94a94e6025ab592ff..e4b1e6449d86bd5be39a4644bbc92d21f726bf6d 100644
--- a/Framework/API/inc/MantidAPI/DetectorSearcher.h
+++ b/Framework/API/inc/MantidAPI/DetectorSearcher.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_DETECTOR_SEARCHER_H_
-#define MANTID_DETECTOR_SEARCHER_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidGeometry/Instrument.h"
@@ -89,4 +88,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/DistributedAlgorithm.h b/Framework/API/inc/MantidAPI/DistributedAlgorithm.h
index 12c6e308c3333cf084aa7bb5d19292a3e08af6aa..7482336ccc01ba8c950c725e4592e4fabd01e3c6 100644
--- a/Framework/API/inc/MantidAPI/DistributedAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/DistributedAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_DISTRIBUTEDALGORITHM_H_
-#define MANTID_API_DISTRIBUTEDALGORITHM_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/DllConfig.h"
@@ -45,4 +44,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_DISTRIBUTEDALGORITHM_H_ */
diff --git a/Framework/API/inc/MantidAPI/DllConfig.h b/Framework/API/inc/MantidAPI/DllConfig.h
index 846a9da71ae504a8fc7b6c08f1893e0eb0314d20..4ae1c17ebcb2751fcfd31b0ae595f9dc37044c5f 100644
--- a/Framework/API/inc/MantidAPI/DllConfig.h
+++ b/Framework/API/inc/MantidAPI/DllConfig.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_DLLCONFIG_H_
-#define MANTID_API_DLLCONFIG_H_
+#pragma once
 
 /*
     This file contains the DLLExport/DLLImport linkage configuration for the
@@ -22,5 +21,3 @@
 #define MANTID_API_DLL DLLImport
 #define EXTERN_MANTID_API EXTERN_IMPORT
 #endif /* IN_MANTID_API*/
-
-#endif // MANTID_API_DLLCONFIG_H_
diff --git a/Framework/API/inc/MantidAPI/DomainCreatorFactory.h b/Framework/API/inc/MantidAPI/DomainCreatorFactory.h
index 3d8fe47ccf9eccb76b9e95d5a744ed99266e4b8e..115ec5d26754f3f45a65291e34904bdc25f1a3e4 100644
--- a/Framework/API/inc/MantidAPI/DomainCreatorFactory.h
+++ b/Framework/API/inc/MantidAPI/DomainCreatorFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_DOMAINCREATORFACTORY_H_
-#define MANTID_API_DOMAINCREATORFACTORY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/DynamicFactory.h"
@@ -71,4 +70,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /* MANTID_API_DOMAINCREATORFACTORY_H_ */
diff --git a/Framework/API/inc/MantidAPI/EnabledWhenWorkspaceIsType.h b/Framework/API/inc/MantidAPI/EnabledWhenWorkspaceIsType.h
index 8c908f65b6dd5ea51876dde6d57a78cbbd70fde4..d29c63705b93b20cfba2e1ad8fd28e53dcec165c 100644
--- a/Framework/API/inc/MantidAPI/EnabledWhenWorkspaceIsType.h
+++ b/Framework/API/inc/MantidAPI/EnabledWhenWorkspaceIsType.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ENABLEDWHENWORKSPACEISTYPE_H_
-#define MANTID_API_ENABLEDWHENWORKSPACEISTYPE_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/Workspace_fwd.h"
@@ -106,4 +105,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_ENABLEDWHENWORKSPACEISTYPE_H_ */
diff --git a/Framework/API/inc/MantidAPI/EqualBinSizesValidator.h b/Framework/API/inc/MantidAPI/EqualBinSizesValidator.h
index 28b5993ce7bc1b87887922d3610079e7f0846283..b22d22698b080e558ad5fa39b257d24e6f2ee7be 100644
--- a/Framework/API/inc/MantidAPI/EqualBinSizesValidator.h
+++ b/Framework/API/inc/MantidAPI/EqualBinSizesValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_EQUALBINSIZESVALIDATOR_H_
-#define MANTID_API_EQUALBINSIZESVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/MatrixWorkspaceValidator.h"
@@ -38,4 +37,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_EQUALBINSIZESVALIDATOR_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/ExperimentInfo.h b/Framework/API/inc/MantidAPI/ExperimentInfo.h
index 52dfcdc18163158a8a5153fd1f71ed7a03645315..c1ae94db189385c63ceecfd99a483fb6fe1d8c28 100644
--- a/Framework/API/inc/MantidAPI/ExperimentInfo.h
+++ b/Framework/API/inc/MantidAPI/ExperimentInfo.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_EXPERIMENTINFO_H_
-#define MANTID_API_EXPERIMENTINFO_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -236,4 +235,3 @@ using ExperimentInfo_const_sptr = boost::shared_ptr<const ExperimentInfo>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_EXPERIMENTINFO_H_ */
diff --git a/Framework/API/inc/MantidAPI/Expression.h b/Framework/API/inc/MantidAPI/Expression.h
index 0c80a0368cd87e2a235a15df498c49e249a258bb..e0fd77d50e918c3ef867c71e8d0557ed2de95ad3 100644
--- a/Framework/API/inc/MantidAPI/Expression.h
+++ b/Framework/API/inc/MantidAPI/Expression.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_EXPRESSION_H
-#define MANTID_API_EXPRESSION_H
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -221,5 +220,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /* EXPRESSION_H */
diff --git a/Framework/API/inc/MantidAPI/FileBackedExperimentInfo.h b/Framework/API/inc/MantidAPI/FileBackedExperimentInfo.h
index 9d17aad67ccfcc3e8b0e2667ac5f56c15fe77d73..1943c80087d371ce80f064061c6840b65360094b 100644
--- a/Framework/API/inc/MantidAPI/FileBackedExperimentInfo.h
+++ b/Framework/API/inc/MantidAPI/FileBackedExperimentInfo.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FILEBACKEDEXPERIMENTINFO_H_
-#define MANTID_API_FILEBACKEDEXPERIMENTINFO_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ExperimentInfo.h"
@@ -35,4 +34,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_FILEBACKEDEXPERIMENTINFO_H_ */
diff --git a/Framework/API/inc/MantidAPI/FileFinder.h b/Framework/API/inc/MantidAPI/FileFinder.h
index 5ce8f4be1c95f4e7bc55a2ff6c5ae3e59ad3a3d2..3ce16b61cff36d1d5597ba955b2ee6f2ce378609 100644
--- a/Framework/API/inc/MantidAPI/FileFinder.h
+++ b/Framework/API/inc/MantidAPI/FileFinder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FILEFINDER_H_
-#define MANTID_API_FILEFINDER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -95,4 +94,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif // MANTID_API_FILEFINDER_H_
diff --git a/Framework/API/inc/MantidAPI/FileLoaderRegistry.h b/Framework/API/inc/MantidAPI/FileLoaderRegistry.h
index 5404841ae5d3ead3b6b835408f38a48514028c31..ea608352ca2a445c5d62be4af0d035f533d2c649 100644
--- a/Framework/API/inc/MantidAPI/FileLoaderRegistry.h
+++ b/Framework/API/inc/MantidAPI/FileLoaderRegistry.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FILELOADERREGISTRY_H_
-#define MANTID_API_FILELOADERREGISTRY_H_
+#pragma once
 
 #include "MantidAPI/AlgorithmFactory.h"
 #include "MantidAPI/IFileLoader.h"
@@ -143,5 +142,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
     Mantid::Kernel::SingletonHolder<Mantid::API::FileLoaderRegistryImpl>;
 }
 } // namespace Mantid
-
-#endif /* MANTID_API_FILELOADERREGISTRY_H_ */
diff --git a/Framework/API/inc/MantidAPI/FileProperty.h b/Framework/API/inc/MantidAPI/FileProperty.h
index 9edf4ca07d9c27d9b2c86f7b1befe88ec0259668..4d7a8463016213524c0347dd6903a6d2b21681b7 100644
--- a/Framework/API/inc/MantidAPI/FileProperty.h
+++ b/Framework/API/inc/MantidAPI/FileProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FILEPROPERTY_H_
-#define MANTID_API_FILEPROPERTY_H_
+#pragma once
 
 //-----------------------------------------------------------------
 // Includes
@@ -128,5 +127,3 @@ private:
 #endif
 } // namespace API
 } // namespace Mantid
-
-#endif // MANTID_API_FILEPROPERTY_H_
diff --git a/Framework/API/inc/MantidAPI/FrameworkManager.h b/Framework/API/inc/MantidAPI/FrameworkManager.h
index f0a785b7cbfd7a162fafdccd239853813cd0227f..b5a43d33e7bcaf76b3024cdc30f870e7b4109cac 100644
--- a/Framework/API/inc/MantidAPI/FrameworkManager.h
+++ b/Framework/API/inc/MantidAPI/FrameworkManager.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FRAMEWORKMANAGER_H_
-#define MANTID_API_FRAMEWORKMANAGER_H_
+#pragma once
 
 #include <string>
 
@@ -131,5 +130,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
     Mantid::Kernel::SingletonHolder<Mantid::API::FrameworkManagerImpl>;
 }
 } // namespace Mantid
-
-#endif /*MANTID_API_FRAMEWORKMANAGER_H_*/
diff --git a/Framework/API/inc/MantidAPI/FuncMinimizerFactory.h b/Framework/API/inc/MantidAPI/FuncMinimizerFactory.h
index afdd6900dbda77d10a5f19c61b64733f98cea376..019b381ad01ab56d6ec1bcb5ed0e0fa8b2fe61bb 100644
--- a/Framework/API/inc/MantidAPI/FuncMinimizerFactory.h
+++ b/Framework/API/inc/MantidAPI/FuncMinimizerFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCMINIMIZERFACTORY_H_
-#define MANTID_API_FUNCMINIMIZERFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -72,4 +71,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
        0));                                                                    \
   }
 
-#endif /*MANTID_API_FUNCMINIMIZERFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionDomain.h b/Framework/API/inc/MantidAPI/FunctionDomain.h
index 6e6d61032a0eac68efc5b6d3d98ce96ac3c20e11..b843bd4e1a9a1a9352c976b7fdcb37844b974303 100644
--- a/Framework/API/inc/MantidAPI/FunctionDomain.h
+++ b/Framework/API/inc/MantidAPI/FunctionDomain.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONDOMAIN_H_
-#define MANTID_API_FUNCTIONDOMAIN_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -45,5 +44,3 @@ using FunctionDomain_sptr = boost::shared_ptr<FunctionDomain>;
 
 } // namespace API
 } // namespace Mantid
-
-#endif /*MANTID_API_FUNCTIONDOMAIN_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionDomain1D.h b/Framework/API/inc/MantidAPI/FunctionDomain1D.h
index 297c1afa23e81eb199db1634940c1d795dba3cbb..5438a7889980c8c6a8df4c2d30d4984b10718d46 100644
--- a/Framework/API/inc/MantidAPI/FunctionDomain1D.h
+++ b/Framework/API/inc/MantidAPI/FunctionDomain1D.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONDOMAIN1D_H_
-#define MANTID_API_FUNCTIONDOMAIN1D_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -165,4 +164,3 @@ using FunctionDomain1D_const_sptr = boost::shared_ptr<const FunctionDomain1D>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_FUNCTIONDOMAIN1D_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionDomainGeneral.h b/Framework/API/inc/MantidAPI/FunctionDomainGeneral.h
index 9ab60e93c4f1f250c30b9db876c109d74780cb68..63075e32890c781c015975f967c8a17d37465a83 100644
--- a/Framework/API/inc/MantidAPI/FunctionDomainGeneral.h
+++ b/Framework/API/inc/MantidAPI/FunctionDomainGeneral.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONDOMAINGENERAL_H_
-#define MANTID_API_FUNCTIONDOMAINGENERAL_H_
+#pragma once
 
 #include "MantidAPI/FunctionDomain.h"
 #include <boost/shared_ptr.hpp>
@@ -38,4 +37,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_FUNCTIONDOMAINGENERAL_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionDomainMD.h b/Framework/API/inc/MantidAPI/FunctionDomainMD.h
index 49650a0aa4d4f0bd664569ce130eb8c6cd09a722..5b0e826dd48d2c51d0a9cfd30b56bf14088dac94 100644
--- a/Framework/API/inc/MantidAPI/FunctionDomainMD.h
+++ b/Framework/API/inc/MantidAPI/FunctionDomainMD.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONDOMAINMD_H_
-#define MANTID_API_FUNCTIONDOMAINMD_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -56,4 +55,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_FUNCTIONDOMAINMD_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionFactory.h b/Framework/API/inc/MantidAPI/FunctionFactory.h
index 33ae48456dc600509e5766a7a7f7cd45366cf8a6..e8674d71a975c6c6388b73e5491f87aea1299333 100644
--- a/Framework/API/inc/MantidAPI/FunctionFactory.h
+++ b/Framework/API/inc/MantidAPI/FunctionFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONFACTORY_H_
-#define MANTID_API_FUNCTIONFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -164,4 +163,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
                                      0));                                      \
   }
 
-#endif /*MANTID_API_FUNCTIONFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionGenerator.h b/Framework/API/inc/MantidAPI/FunctionGenerator.h
index f5fde4142a01e3047084b673b010f869c0270e7e..a73ca5d58fa2253fd225b5c16b092a16abc903b8 100644
--- a/Framework/API/inc/MantidAPI/FunctionGenerator.h
+++ b/Framework/API/inc/MantidAPI/FunctionGenerator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONGENERATOR_H_
-#define MANTID_API_FUNCTIONGENERATOR_H_
+#pragma once
 
 #include "MantidAPI/IFunction.h"
 
@@ -135,4 +134,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_FUNCTIONGENERATOR_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h b/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h
index fafcd59a2d26a247d284b6e1992beaf40088f5e7..21410e59f6509c7b663fbefdc742d52f9224cde5 100644
--- a/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h
+++ b/Framework/API/inc/MantidAPI/FunctionParameterDecorator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONPARAMETERDECORATOR_H_
-#define MANTID_API_FUNCTIONPARAMETERDECORATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/IFunction.h"
@@ -142,4 +141,3 @@ using FunctionParameterDecorator_sptr =
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_FUNCTIONPARAMETERDECORATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/FunctionProperty.h b/Framework/API/inc/MantidAPI/FunctionProperty.h
index 9e3ddbe6f31831487cf0bb511a18742f2f04d7e2..ad3d09615c0751cb121ec15e4f82c2be936592d3 100644
--- a/Framework/API/inc/MantidAPI/FunctionProperty.h
+++ b/Framework/API/inc/MantidAPI/FunctionProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONPROPERTY_H_
-#define MANTID_API_FUNCTIONPROPERTY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -85,4 +84,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_FUNCTIONPROPERTY_H_*/
diff --git a/Framework/API/inc/MantidAPI/FunctionValues.h b/Framework/API/inc/MantidAPI/FunctionValues.h
index 6b84d72c48a95b0d465abb17479fe49ab55f565e..4979b886ab707cdb786f11284378af6a92d76979 100644
--- a/Framework/API/inc/MantidAPI/FunctionValues.h
+++ b/Framework/API/inc/MantidAPI/FunctionValues.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FUNCTIONVALUES_H_
-#define MANTID_API_FUNCTIONVALUES_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -111,4 +110,3 @@ using FunctionValues_sptr = boost::shared_ptr<FunctionValues>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_FUNCTIONVALUES_H_*/
diff --git a/Framework/API/inc/MantidAPI/GridDomain.h b/Framework/API/inc/MantidAPI/GridDomain.h
index f480a205cb8c3be3ef1f0288fb57eee37ce82508..1a6f480ced698578d2f03a984448d92c6f4c62a9 100644
--- a/Framework/API/inc/MantidAPI/GridDomain.h
+++ b/Framework/API/inc/MantidAPI/GridDomain.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_GRIDDOMAIN_H_
-#define MANTID_API_GRIDDOMAIN_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -48,4 +47,3 @@ using GridDomain_sptr = boost::shared_ptr<GridDomain>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_GRIDDOMAIN_H_*/
diff --git a/Framework/API/inc/MantidAPI/GridDomain1D.h b/Framework/API/inc/MantidAPI/GridDomain1D.h
index e7b1f51126c4eda6420b2bf8f4969880388424a3..3b9cab8266060af9e2a44e686ed029dbac81929c 100644
--- a/Framework/API/inc/MantidAPI/GridDomain1D.h
+++ b/Framework/API/inc/MantidAPI/GridDomain1D.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_GRIDDOMAIN1D_H_
-#define MANTID_API_GRIDDOMAIN1D_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -48,4 +47,3 @@ using GridDomain1D_sptr = boost::shared_ptr<GridDomain1D>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_GRIDDOMAIN1D_H_*/
diff --git a/Framework/API/inc/MantidAPI/GroupingLoader.h b/Framework/API/inc/MantidAPI/GroupingLoader.h
index 5f751d9700ec0319e98f7865931459ef62630f71..4df62f02f5fa7b172191761c50a1e61a354bbd19 100644
--- a/Framework/API/inc/MantidAPI/GroupingLoader.h
+++ b/Framework/API/inc/MantidAPI/GroupingLoader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_GROUPINGLOADER_H_
-#define MANTID_API_GROUPINGLOADER_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ITableWorkspace_fwd.h"
@@ -66,4 +65,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_GROUPINGLOADER_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/HistoWorkspace.h b/Framework/API/inc/MantidAPI/HistoWorkspace.h
index 1f424adf34a17cb13e203dab9e98704182217a81..53f536bf2433f6b389848c656724de6195c1c519 100644
--- a/Framework/API/inc/MantidAPI/HistoWorkspace.h
+++ b/Framework/API/inc/MantidAPI/HistoWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_HISTOWORKSPACE_H_
-#define MANTID_API_HISTOWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/MatrixWorkspace.h"
@@ -44,4 +43,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_HISTOWORKSPACE_H_ */
diff --git a/Framework/API/inc/MantidAPI/HistogramValidator.h b/Framework/API/inc/MantidAPI/HistogramValidator.h
index cc32b2302be8431d1b69df6e7f24ba8409072230..667c6b0a6af1a2c06663369feddc8305a4b6accc 100644
--- a/Framework/API/inc/MantidAPI/HistogramValidator.h
+++ b/Framework/API/inc/MantidAPI/HistogramValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_HISTOGRAMVALIDATOR_H_
-#define MANTID_API_HISTOGRAMVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -37,4 +36,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_HISTOGRAMVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/HistoryItem.h b/Framework/API/inc/MantidAPI/HistoryItem.h
index b20bee1285644a1e7a419c55ca7e1de12bb56b15..17573235d4728677ce3ac1a95f90ad8637d3d98b 100644
--- a/Framework/API/inc/MantidAPI/HistoryItem.h
+++ b/Framework/API/inc/MantidAPI/HistoryItem.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_HISTORYITEM_H_
-#define MANTID_API_HISTORYITEM_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -46,4 +45,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_HISTORYITEM_H_*/
diff --git a/Framework/API/inc/MantidAPI/HistoryView.h b/Framework/API/inc/MantidAPI/HistoryView.h
index 49e508a80e33b5bd769f80e3bfb2f2df6d8b7d6d..8f41ac5961d6a2e421121b23377753873f0ab569 100644
--- a/Framework/API/inc/MantidAPI/HistoryView.h
+++ b/Framework/API/inc/MantidAPI/HistoryView.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_HISTORYVIEW_H_
-#define MANTID_API_HISTORYVIEW_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -65,4 +64,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_HISTORYVIEW_H_*/
diff --git a/Framework/API/inc/MantidAPI/IAlgorithm.h b/Framework/API/inc/MantidAPI/IAlgorithm.h
index 4df10263a59e00310a193c10f62efe59446695ec..b3b44aec107d3c4ba89ced229aff0b078f5ef122 100644
--- a/Framework/API/inc/MantidAPI/IAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/IAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IALGORITHM_H_
-#define MANTID_API_IALGORITHM_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -178,4 +177,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_KERNEL_IALGORITHM_H_*/
diff --git a/Framework/API/inc/MantidAPI/IAlgorithm_fwd.h b/Framework/API/inc/MantidAPI/IAlgorithm_fwd.h
index 6359214884de5a0963023c06d56500401c3ba5e4..af8ece39dc07cfec50c840e653b7864f99dd1959 100644
--- a/Framework/API/inc/MantidAPI/IAlgorithm_fwd.h
+++ b/Framework/API/inc/MantidAPI/IAlgorithm_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IALGORITHM_FWD_H_
-#define MANTID_API_IALGORITHM_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -30,4 +29,3 @@ using IAlgorithm_const_uptr = std::unique_ptr<const IAlgorithm>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_IALGORITHM_FWD_H_
diff --git a/Framework/API/inc/MantidAPI/IArchiveSearch.h b/Framework/API/inc/MantidAPI/IArchiveSearch.h
index 46b5840dbb7d0ac005d84ebd9d862157c633a881..a4f0a809e2325ce56bc7a77df431ff721884b07d 100644
--- a/Framework/API/inc/MantidAPI/IArchiveSearch.h
+++ b/Framework/API/inc/MantidAPI/IArchiveSearch.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IARCHIVESEARCH_H_
-#define MANTID_API_IARCHIVESEARCH_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -56,5 +55,3 @@ public:
 using IArchiveSearch_sptr = boost::shared_ptr<IArchiveSearch>;
 } // namespace API
 } // namespace Mantid
-
-#endif // MANTID_API_IARCHIVESEARCH_H_
diff --git a/Framework/API/inc/MantidAPI/IBackgroundFunction.h b/Framework/API/inc/MantidAPI/IBackgroundFunction.h
index b2033faffe8c3a391d2ddd9eb6b37fd7a6d3f25b..93aa9fc8e004f0cd72d87c50def3155a307ce607 100644
--- a/Framework/API/inc/MantidAPI/IBackgroundFunction.h
+++ b/Framework/API/inc/MantidAPI/IBackgroundFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IBACKGROUNDFUNCTION_H_
-#define MANTID_API_IBACKGROUNDFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -34,4 +33,3 @@ using IBackgroundFunction_sptr = boost::shared_ptr<IBackgroundFunction>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IBACKGROUNDFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/IBoxControllerIO.h b/Framework/API/inc/MantidAPI/IBoxControllerIO.h
index 4bf2152b2c04eefa2cde928144d4c7628d4c5f90..15f18add2bc502b9f6bf60444461fb4915cfcc9b 100644
--- a/Framework/API/inc/MantidAPI/IBoxControllerIO.h
+++ b/Framework/API/inc/MantidAPI/IBoxControllerIO.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef H_IBOXCONTROLLER_IO
-#define H_IBOXCONTROLLER_IO
+#pragma once
 #include "MantidKernel/DiskBuffer.h"
 #include "MantidKernel/System.h"
 
@@ -72,4 +71,3 @@ public:
 };
 } // namespace API
 } // namespace Mantid
-#endif
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/ICatalog.h b/Framework/API/inc/MantidAPI/ICatalog.h
index 290dae25fa0a6f839746b1c158052640ffd45f46..7d39849bfafa67a5c2d825b3c5975a810ba934de 100644
--- a/Framework/API/inc/MantidAPI/ICatalog.h
+++ b/Framework/API/inc/MantidAPI/ICatalog.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ICATLOG_H_
-#define MANTID_API_ICATLOG_H_
+#pragma once
 
 #include "MantidAPI/CatalogSession.h"
 #include "MantidAPI/ITableWorkspace_fwd.h"
@@ -61,4 +60,3 @@ using ICatalog_const_sptr = boost::shared_ptr<const ICatalog>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ICATLOG_H_*/
diff --git a/Framework/API/inc/MantidAPI/ICatalogInfoService.h b/Framework/API/inc/MantidAPI/ICatalogInfoService.h
index 9e58b9dd2fd6ebe3dc8b991f010d2b7132d7fbeb..6ef7c455d7656e277fbbd7aafa3694b0aae9476e 100644
--- a/Framework/API/inc/MantidAPI/ICatalogInfoService.h
+++ b/Framework/API/inc/MantidAPI/ICatalogInfoService.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ICATLOGINFOSERVICE_H_
-#define MANTID_API_ICATLOGINFOSERVICE_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ITableWorkspace_fwd.h"
@@ -43,4 +42,3 @@ using ICatalogInfoService_const_sptr =
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ICATLOGINFOSERVICE_H_*/
diff --git a/Framework/API/inc/MantidAPI/IConstraint.h b/Framework/API/inc/MantidAPI/IConstraint.h
index 75070c3c010bfdfb01a40f1de6ea8afd5300924e..3bee9174c63e1650a54821c52a3d4417ae3b3952 100644
--- a/Framework/API/inc/MantidAPI/IConstraint.h
+++ b/Framework/API/inc/MantidAPI/IConstraint.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ICONSTRAINT_H_
-#define MANTID_API_ICONSTRAINT_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -73,4 +72,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ICONSTRAINT_H_*/
diff --git a/Framework/API/inc/MantidAPI/ICostFunction.h b/Framework/API/inc/MantidAPI/ICostFunction.h
index 9e848f62c7de51a7515a9fb7d70ec0a684e9f7c6..f249ddac8cceb65344d681d026f50cd25205907e 100644
--- a/Framework/API/inc/MantidAPI/ICostFunction.h
+++ b/Framework/API/inc/MantidAPI/ICostFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ICOSTFUNCTION_H_
-#define MANTID_API_ICOSTFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -75,4 +74,3 @@ using ICostFunction_sptr = boost::shared_ptr<ICostFunction>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ICOSTFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/IDomainCreator.h b/Framework/API/inc/MantidAPI/IDomainCreator.h
index ed28e4f6ff9c70744c1e3c7cc94bd0e80fccd748..35c72bad301c14c7747f8cf12b965b459276bb88 100644
--- a/Framework/API/inc/MantidAPI/IDomainCreator.h
+++ b/Framework/API/inc/MantidAPI/IDomainCreator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IDOMAINCREATOR_H_
-#define MANTID_API_IDOMAINCREATOR_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -151,4 +150,3 @@ using IDomainCreator_sptr = boost::shared_ptr<IDomainCreator>;
                                 0));                                           \
   }
 
-#endif /*MANTID_API_IDOMAINCREATOR_H_*/
diff --git a/Framework/API/inc/MantidAPI/IEventList.h b/Framework/API/inc/MantidAPI/IEventList.h
index 084b067e443e429944663a7707adfe0c21fa88f8..13758435d772a871557de3e21ee323cd3b7b7c44 100644
--- a/Framework/API/inc/MantidAPI/IEventList.h
+++ b/Framework/API/inc/MantidAPI/IEventList.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IEVENTLIST_H_
-#define MANTID_API_IEVENTLIST_H_
+#pragma once
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ISpectrum.h"
 #include "MantidAPI/MatrixWorkspace_fwd.h"
@@ -129,4 +128,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IEVENTLIST_H_ */
diff --git a/Framework/API/inc/MantidAPI/IEventWorkspace.h b/Framework/API/inc/MantidAPI/IEventWorkspace.h
index b93b5de3aa95c7f8e039a091cfdd88146cd70285..fa75e6858b7ded861f9eeb34f0354eea92b1c752 100644
--- a/Framework/API/inc/MantidAPI/IEventWorkspace.h
+++ b/Framework/API/inc/MantidAPI/IEventWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IEVENTWORKSPACE_H_
-#define MANTID_API_IEVENTWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/IEventList.h"
 #include "MantidAPI/IEventWorkspace_fwd.h"
@@ -71,4 +70,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_IEVENTWORKSPACE_H_
diff --git a/Framework/API/inc/MantidAPI/IEventWorkspace_fwd.h b/Framework/API/inc/MantidAPI/IEventWorkspace_fwd.h
index 737c0bdf06353298fbf1402e23af6b1bf134c815..23502039665e071ba24345582d6a6f56695eb731 100644
--- a/Framework/API/inc/MantidAPI/IEventWorkspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/IEventWorkspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IEVENTWORKSPACE_FWD_H_
-#define MANTID_API_IEVENTWORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -30,4 +29,3 @@ using IEventWorkspace_const_uptr = std::unique_ptr<const IEventWorkspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_IEVENTWORKSPACE_FWD_H_
diff --git a/Framework/API/inc/MantidAPI/IFileLoader.h b/Framework/API/inc/MantidAPI/IFileLoader.h
index 4d0caa463ab8c0880ea379450341d54d47661e46..018523394137d9ae5ba80b8e7908aea9e004de86 100644
--- a/Framework/API/inc/MantidAPI/IFileLoader.h
+++ b/Framework/API/inc/MantidAPI/IFileLoader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFILELOADER_H_
-#define MANTID_API_IFILELOADER_H_
+#pragma once
 
 #include "MantidAPI/ParallelAlgorithm.h"
 #include "MantidKernel/FileDescriptor.h"
@@ -32,4 +31,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IFILELOADER_H_ */
diff --git a/Framework/API/inc/MantidAPI/IFuncMinimizer.h b/Framework/API/inc/MantidAPI/IFuncMinimizer.h
index be301d13a9ff28ebe24e72a43ba7b3263d242f39..24c97b6cb7806083f7b7cba620dcbb407ca73fa0 100644
--- a/Framework/API/inc/MantidAPI/IFuncMinimizer.h
+++ b/Framework/API/inc/MantidAPI/IFuncMinimizer.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCMINIMIZER_H_
-#define MANTID_API_IFUNCMINIMIZER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -64,4 +63,3 @@ using IFuncMinimizer_sptr = boost::shared_ptr<IFuncMinimizer>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IFUNCMINIMIZER_H_*/
diff --git a/Framework/API/inc/MantidAPI/IFunction1D.h b/Framework/API/inc/MantidAPI/IFunction1D.h
index 44e95eeeb1998e2fe4f52c34005c0c9a0451f1d2..b980e4fa5ac537d256fb7729dfe24e0f6170f6f7 100644
--- a/Framework/API/inc/MantidAPI/IFunction1D.h
+++ b/Framework/API/inc/MantidAPI/IFunction1D.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTION1D_H_
-#define MANTID_API_IFUNCTION1D_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -92,4 +91,3 @@ using IFunction1D_sptr = boost::shared_ptr<IFunction1D>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IFUNCTION1D_H_*/
diff --git a/Framework/API/inc/MantidAPI/IFunction1DSpectrum.h b/Framework/API/inc/MantidAPI/IFunction1DSpectrum.h
index 4f8452c8782f29c9ae727b65a5811d86d36da25c..3fbd845bd9a8fe11f03672b6312c199357dde1e5 100644
--- a/Framework/API/inc/MantidAPI/IFunction1DSpectrum.h
+++ b/Framework/API/inc/MantidAPI/IFunction1DSpectrum.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTION1DSPECTRUM_H_
-#define MANTID_API_IFUNCTION1DSPECTRUM_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -47,4 +46,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IFUNCTION1DSPECTRUM_H_ */
diff --git a/Framework/API/inc/MantidAPI/IFunctionGeneral.h b/Framework/API/inc/MantidAPI/IFunctionGeneral.h
index f30a12f6808663ed500ccde293c0e9fb9839f9a5..b03027ecc5d8423e41146be18164cf87b7c6e49e 100644
--- a/Framework/API/inc/MantidAPI/IFunctionGeneral.h
+++ b/Framework/API/inc/MantidAPI/IFunctionGeneral.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTIONGENERAL_H_
-#define MANTID_API_IFUNCTIONGENERAL_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -59,4 +58,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IFUNCTIONGENERAL_H_ */
diff --git a/Framework/API/inc/MantidAPI/IFunctionMD.h b/Framework/API/inc/MantidAPI/IFunctionMD.h
index e99e87722006f710057190c95871efda342a0814..3cb9932b7aa45196c37b7d16fc75ee7d0c9ea1fe 100644
--- a/Framework/API/inc/MantidAPI/IFunctionMD.h
+++ b/Framework/API/inc/MantidAPI/IFunctionMD.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTIONMD_H_
-#define MANTID_API_IFUNCTIONMD_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -91,5 +90,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /*MANTID_API_IFUNCTIONMD_H_*/
diff --git a/Framework/API/inc/MantidAPI/IFunctionMW.h b/Framework/API/inc/MantidAPI/IFunctionMW.h
index 9fc9e36315637732025bc9d6e8330159558107b2..6a0d7ea8d48bd98339958c7ea43d67c528c970ff 100644
--- a/Framework/API/inc/MantidAPI/IFunctionMW.h
+++ b/Framework/API/inc/MantidAPI/IFunctionMW.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTIONMW_H_
-#define MANTID_API_IFUNCTIONMW_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -48,5 +47,3 @@ protected:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /*MANTID_API_IFUNCTIONMW_H_*/
diff --git a/Framework/API/inc/MantidAPI/IFunctionWithLocation.h b/Framework/API/inc/MantidAPI/IFunctionWithLocation.h
index 87172ea11e8165a6b4676b4ebbc866b3629f0e4d..4f21b2a6eb4056ed208e93bec541ac594e1d442b 100644
--- a/Framework/API/inc/MantidAPI/IFunctionWithLocation.h
+++ b/Framework/API/inc/MantidAPI/IFunctionWithLocation.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IIFUNCTIONWITHLOCATION_H_
-#define MANTID_API_IIFUNCTIONWITHLOCATION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -70,4 +69,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IIFUNCTIONWITHLOCATION_H_*/
diff --git a/Framework/API/inc/MantidAPI/IFunction_fwd.h b/Framework/API/inc/MantidAPI/IFunction_fwd.h
index ca11c602df687c48001fd8141fe0eed5e6cc9961..5a25072be5f4d1ad4dc9406cdf46e619d7bd0c48 100644
--- a/Framework/API/inc/MantidAPI/IFunction_fwd.h
+++ b/Framework/API/inc/MantidAPI/IFunction_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IFUNCTION_FWD_H_
-#define IFUNCTION_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -42,4 +41,3 @@ using MultiDomainFunction_const_sptr =
 } // namespace API
 } // namespace Mantid
 
-#endif /* IFUNCTION_FWD_H_ */
diff --git a/Framework/API/inc/MantidAPI/ILatticeFunction.h b/Framework/API/inc/MantidAPI/ILatticeFunction.h
index f2eea27a2ef6dbff86811ce78f68505c0d4934a5..3c825cfa8742bcce61fd2f9e5e1d4f2a49e77c8c 100644
--- a/Framework/API/inc/MantidAPI/ILatticeFunction.h
+++ b/Framework/API/inc/MantidAPI/ILatticeFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ILATTICEFUNCTION_H_
-#define MANTID_API_ILATTICEFUNCTION_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/FunctionParameterDecorator.h"
@@ -57,4 +56,3 @@ using ILatticeFunction_sptr = boost::shared_ptr<ILatticeFunction>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_ILATTICEFUNCTION_H_ */
diff --git a/Framework/API/inc/MantidAPI/ILiveListener.h b/Framework/API/inc/MantidAPI/ILiveListener.h
index e64f2665e99ae9e6af4802b50a8b76c394fc7412..51f2047521fc97f38218d867917518d2cff98b83 100644
--- a/Framework/API/inc/MantidAPI/ILiveListener.h
+++ b/Framework/API/inc/MantidAPI/ILiveListener.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ILIVELISTENER_H_
-#define MANTID_API_ILIVELISTENER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -139,4 +138,3 @@ using ILiveListener_sptr = boost::shared_ptr<ILiveListener>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_ILIVELISTENER_H_*/
diff --git a/Framework/API/inc/MantidAPI/IMDEventWorkspace.h b/Framework/API/inc/MantidAPI/IMDEventWorkspace.h
index 60a559c99955e9b934bfed06204ba8c3527c4856..3604522adcb7647b8bdce1983fa8f99bf73fa3ba 100644
--- a/Framework/API/inc/MantidAPI/IMDEventWorkspace.h
+++ b/Framework/API/inc/MantidAPI/IMDEventWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMDEVENTWORKSPACE_H_
-#define IMDEVENTWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/BoxController.h"
 #include "MantidAPI/DllConfig.h"
@@ -135,4 +134,3 @@ private:
 
 } // namespace Mantid
 
-#endif /* IMDEVENTWORKSPACE_H_ */
diff --git a/Framework/API/inc/MantidAPI/IMDEventWorkspace_fwd.h b/Framework/API/inc/MantidAPI/IMDEventWorkspace_fwd.h
index f2576b6a593cbee43c94ebf42bdb450241fe792c..73f9c730bc4923caeb71632e9c048a836c55b18b 100644
--- a/Framework/API/inc/MantidAPI/IMDEventWorkspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/IMDEventWorkspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMDEVENTWORKSPACE_FWD_H_
-#define IMDEVENTWORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -31,4 +30,3 @@ using IMDEventWorkspace_const_uptr = std::unique_ptr<const IMDEventWorkspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* IMDEVENTWORKSPACE_FWD_H_ */
diff --git a/Framework/API/inc/MantidAPI/IMDHistoWorkspace.h b/Framework/API/inc/MantidAPI/IMDHistoWorkspace.h
index 048f8624cbd2c93eab095dde05157cb1301212a7..e3e6fc266a942b635c239926574b0a9c6289a04d 100644
--- a/Framework/API/inc/MantidAPI/IMDHistoWorkspace.h
+++ b/Framework/API/inc/MantidAPI/IMDHistoWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IMDHISTOWORKSPACE_H_
-#define MANTID_API_IMDHISTOWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/IMDHistoWorkspace_fwd.h"
 #include "MantidAPI/IMDWorkspace.h"
@@ -114,4 +113,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IMDHISTOWORKSPACE_H_ */
diff --git a/Framework/API/inc/MantidAPI/IMDHistoWorkspace_fwd.h b/Framework/API/inc/MantidAPI/IMDHistoWorkspace_fwd.h
index feab0eaa8b98b7b41915e623178fa56326a699bf..c03abd747b757ab3841860e87dee09da1feba436 100644
--- a/Framework/API/inc/MantidAPI/IMDHistoWorkspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/IMDHistoWorkspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IMDHISTOWORKSPACE_FWD_H_
-#define MANTID_API_IMDHISTOWORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -30,4 +29,3 @@ using IMDHistoWorkspace_const_uptr = std::unique_ptr<const IMDHistoWorkspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IMDHISTOWORKSPACE_FWD_H_ */
diff --git a/Framework/API/inc/MantidAPI/IMDIterator.h b/Framework/API/inc/MantidAPI/IMDIterator.h
index 0f8c4cb1f3952fa93fda2e4ad30de13032d2ac1e..861267398c5f35843d0428da8ef6ab64d693bcd7 100644
--- a/Framework/API/inc/MantidAPI/IMDIterator.h
+++ b/Framework/API/inc/MantidAPI/IMDIterator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFMDITERATOR_H_
-#define MANTID_API_IFMDITERATOR_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -128,4 +127,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IFMDITERATOR_H_*/
diff --git a/Framework/API/inc/MantidAPI/IMDNode.h b/Framework/API/inc/MantidAPI/IMDNode.h
index 97a29315194cd0a76faf1b0ee7b5687a8945dc4d..acbf8a44f1f72e6cf69a623bfa732e30200f7e34 100644
--- a/Framework/API/inc/MantidAPI/IMDNode.h
+++ b/Framework/API/inc/MantidAPI/IMDNode.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMD_NODE_H_
-#define IMD_NODE_H_
+#pragma once
 
 #include "MantidGeometry/MDGeometry/MDTypes.h"
 #include "MantidKernel/VMD.h"
@@ -317,4 +316,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/IMDWorkspace.h b/Framework/API/inc/MantidAPI/IMDWorkspace.h
index 51fb1f40dc6073b8ff2c1739c993e45748456091..5ad8a9146b8015eb8b4bd5d97d064541de648ebf 100644
--- a/Framework/API/inc/MantidAPI/IMDWorkspace.h
+++ b/Framework/API/inc/MantidAPI/IMDWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IMDWORKSPACE_H_
-#define MANTID_API_IMDWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/IMDIterator.h"
 #include "MantidAPI/ITableWorkspace_fwd.h"
@@ -166,4 +165,3 @@ using IMDWorkspace_sptr = boost::shared_ptr<IMDWorkspace>;
 using IMDWorkspace_const_sptr = boost::shared_ptr<const IMDWorkspace>;
 } // namespace API
 } // namespace Mantid
-#endif // MANTID_API_IMDWORKSPACE_H_
diff --git a/Framework/API/inc/MantidAPI/IMaskWorkspace.h b/Framework/API/inc/MantidAPI/IMaskWorkspace.h
index 414431987d41a1dd8c25a4684cb269945f02da12..d8868d44f5037b9c2bd7b249046989e0fa25c707 100644
--- a/Framework/API/inc/MantidAPI/IMaskWorkspace.h
+++ b/Framework/API/inc/MantidAPI/IMaskWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IMASKWORKSPACE_H_
-#define MANTID_API_IMASKWORKSPACE_H_
+#pragma once
 
 #include "MantidGeometry/IDTypes.h"
 
@@ -57,4 +56,3 @@ using IMaskWorkspace_const_sptr = boost::shared_ptr<const IMaskWorkspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_IMASKWORKSPACE_H_
diff --git a/Framework/API/inc/MantidAPI/IPawleyFunction.h b/Framework/API/inc/MantidAPI/IPawleyFunction.h
index 91487f26d3dc6ca1fed7db5a2b52bb95c65ac0f9..c7f857c1d289c8c2a098be869642e8ef65562d9f 100644
--- a/Framework/API/inc/MantidAPI/IPawleyFunction.h
+++ b/Framework/API/inc/MantidAPI/IPawleyFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IPAWLEYFUNCTION_H_
-#define MANTID_API_IPAWLEYFUNCTION_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/FunctionParameterDecorator.h"
@@ -61,4 +60,3 @@ using IPawleyFunction_sptr = boost::shared_ptr<IPawleyFunction>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_IPAWLEYFUNCTION_H_ */
diff --git a/Framework/API/inc/MantidAPI/IPeakFunction.h b/Framework/API/inc/MantidAPI/IPeakFunction.h
index 24f4daea30110cf1dce1b7bfd7e5dba848974015..f92a5e69ed451b62dd95b66231e0e1fe493cbc73 100644
--- a/Framework/API/inc/MantidAPI/IPeakFunction.h
+++ b/Framework/API/inc/MantidAPI/IPeakFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IPEAKFUNCTION_H_
-#define MANTID_API_IPEAKFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -94,4 +93,3 @@ using IPeakFunction_const_sptr = boost::shared_ptr<const IPeakFunction>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IPEAKFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/IPeaksWorkspace.h b/Framework/API/inc/MantidAPI/IPeaksWorkspace.h
index 377cd288ed497d496a2f8099bcede950e18a7831..f34d276ceead88966592bb17cca85d830e83e5c6 100644
--- a/Framework/API/inc/MantidAPI/IPeaksWorkspace.h
+++ b/Framework/API/inc/MantidAPI/IPeaksWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IPEAKSWORKSPACE_H_
-#define MANTID_API_IPEAKSWORKSPACE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -177,4 +176,3 @@ private:
 };
 } // namespace API
 } // namespace Mantid
-#endif
diff --git a/Framework/API/inc/MantidAPI/IPeaksWorkspace_fwd.h b/Framework/API/inc/MantidAPI/IPeaksWorkspace_fwd.h
index 7b041b735d868f5e9647d9af1aca71f13bc7aa4b..7f3be834cb30a598a11da47288acccbd0d6edaf2 100644
--- a/Framework/API/inc/MantidAPI/IPeaksWorkspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/IPeaksWorkspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IPEAKWORKSPACE_FWD_H_
-#define MANTID_API_IPEAKWORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -28,4 +27,3 @@ using IPeaksWorkspace_uptr = std::unique_ptr<IPeaksWorkspace>;
 using IPeaksWorkspace_const_uptr = std::unique_ptr<const IPeaksWorkspace>;
 } // namespace API
 } // namespace Mantid
-#endif // MANTID_API_IPEAKWORKSPACE_FWD_H_
diff --git a/Framework/API/inc/MantidAPI/IPowderDiffPeakFunction.h b/Framework/API/inc/MantidAPI/IPowderDiffPeakFunction.h
index a3d62256a6a105fc05603776c13aabb95edc0b25..c1891b033173a6137ae63f50207f19c50c6806e2 100644
--- a/Framework/API/inc/MantidAPI/IPowderDiffPeakFunction.h
+++ b/Framework/API/inc/MantidAPI/IPowderDiffPeakFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IPOWDERDIFFPEAKFUNCTION_H_
-#define MANTID_API_IPOWDERDIFFPEAKFUNCTION_H_
+#pragma once
 
 #include "MantidAPI/IFunction1D.h"
 #include "MantidAPI/ParamFunction.h"
@@ -152,4 +151,3 @@ std::complex<double> MANTID_API_DLL E1(std::complex<double> z);
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IPOWDERDIFFPEAKFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/IRemoteJobManager.h b/Framework/API/inc/MantidAPI/IRemoteJobManager.h
index f80a7a799de5a85f5adc77e78ae9099410b64d4e..6149ba9999477c1bbb65c4ba5a322393e1304f87 100644
--- a/Framework/API/inc/MantidAPI/IRemoteJobManager.h
+++ b/Framework/API/inc/MantidAPI/IRemoteJobManager.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_KERNEL_IREMOTEJOBMANAGER_H
-#define MANTID_KERNEL_IREMOTEJOBMANAGER_H
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/DateAndTime.h"
@@ -279,4 +278,3 @@ using IRemoteJobManager_sptr = boost::shared_ptr<IRemoteJobManager>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_IREMOTEJOBMANAGER_H
diff --git a/Framework/API/inc/MantidAPI/ISpectrum.h b/Framework/API/inc/MantidAPI/ISpectrum.h
index 1f3c03b64835813acf2185f9f7bf023d256fe366..aed11cee5f08aa403ee855e2b2dac6c20c741eba 100644
--- a/Framework/API/inc/MantidAPI/ISpectrum.h
+++ b/Framework/API/inc/MantidAPI/ISpectrum.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ISPECTRUM_H_
-#define MANTID_API_ISPECTRUM_H_
+#pragma once
 
 #include "MantidGeometry/IDTypes.h"
 #include "MantidHistogramData/Histogram.h"
@@ -271,4 +270,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_ISPECTRUM_H_ */
diff --git a/Framework/API/inc/MantidAPI/ISplittersWorkspace.h b/Framework/API/inc/MantidAPI/ISplittersWorkspace.h
index 6d81d65c4eb77163cc7510e376a3dbea4d47c012..5ba645f3deab8f459366a32d835a774c1ec42e2c 100644
--- a/Framework/API/inc/MantidAPI/ISplittersWorkspace.h
+++ b/Framework/API/inc/MantidAPI/ISplittersWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ISPLITTERSWORKSPACE_H_
-#define MANTID_API_ISPLITTERSWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/TimeSplitter.h"
@@ -73,4 +72,3 @@ using ISplittersWorkspace_const_sptr =
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_ISPLITTERSWORKSPACE_H_ */
diff --git a/Framework/API/inc/MantidAPI/ITableWorkspace.h b/Framework/API/inc/MantidAPI/ITableWorkspace.h
index 3a063107139e3747e22cbffa2bb9c79be070dc3d..a3b12c839cfc1611d66ea21c9ef6377a5873abd6 100644
--- a/Framework/API/inc/MantidAPI/ITableWorkspace.h
+++ b/Framework/API/inc/MantidAPI/ITableWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ITABLEWORKSPACE_H_
-#define MANTID_API_ITABLEWORKSPACE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -410,4 +409,3 @@ private:
 
 } // namespace API
 } // Namespace Mantid
-#endif /*MANTID_API_ITABLEWORKSPACE_H_*/
diff --git a/Framework/API/inc/MantidAPI/ITableWorkspace_fwd.h b/Framework/API/inc/MantidAPI/ITableWorkspace_fwd.h
index 0412c4c6291b69eb342f0b00992515f39b8c1755..83265ade539ac92ce2cc0f839d396be3a187c72b 100644
--- a/Framework/API/inc/MantidAPI/ITableWorkspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/ITableWorkspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ITABLEWORKSPACE_FWD_H_
-#define MANTID_API_ITABLEWORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -29,4 +28,3 @@ using ITableWorkspace_const_uptr = std::unique_ptr<const ITableWorkspace>;
 
 } // namespace API
 } // Namespace Mantid
-#endif // MANTID_API_ITABLEWORKSPACE_FWD_H_
diff --git a/Framework/API/inc/MantidAPI/ITransformScale.h b/Framework/API/inc/MantidAPI/ITransformScale.h
index 61ac75804110b977f7e51900c4fe8715142e4f68..abb06dbbb24bd6fc1f8b790d7aa60b0fc86e1891 100644
--- a/Framework/API/inc/MantidAPI/ITransformScale.h
+++ b/Framework/API/inc/MantidAPI/ITransformScale.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ITRANSFORMSCALE_H_
-#define MANTID_API_ITRANSFORMSCALE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -51,5 +50,3 @@ using ITransformScale_sptr = boost::shared_ptr<ITransformScale>;
            #classname)),                                                       \
        0));                                                                    \
   }
-
-#endif /*MANTID_API_ITRANSFORMSCALE_H_*/
diff --git a/Framework/API/inc/MantidAPI/IWorkspaceProperty.h b/Framework/API/inc/MantidAPI/IWorkspaceProperty.h
index d45d393cefd5c295cba8500d6377560196482e2f..439df3f4d48b3f39d72d3ed9e841a5a341310fab 100644
--- a/Framework/API/inc/MantidAPI/IWorkspaceProperty.h
+++ b/Framework/API/inc/MantidAPI/IWorkspaceProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IWORKSPACEPROPERTY_H_
-#define MANTID_API_IWORKSPACEPROPERTY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -42,4 +41,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IWORKSPACEPROPERTY_H_*/
diff --git a/Framework/API/inc/MantidAPI/ImmutableCompositeFunction.h b/Framework/API/inc/MantidAPI/ImmutableCompositeFunction.h
index 486fac7da1e10b00541ccebb50c3dd34c3115457..c8dddefdbbec81a478925ad12ab024932afc309f 100644
--- a/Framework/API/inc/MantidAPI/ImmutableCompositeFunction.h
+++ b/Framework/API/inc/MantidAPI/ImmutableCompositeFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IMMUTABLECOMPOSITEFUNCTION_H_
-#define MANTID_API_IMMUTABLECOMPOSITEFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -80,4 +79,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_IMMUTABLECOMPOSITEFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionBuilder.h b/Framework/API/inc/MantidAPI/ImplicitFunctionBuilder.h
index d98bcfbd53a67582f98d76582a93fc5a8716c42a..5387970f5a0dd869ac21048df94f96047e937e56 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionBuilder.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionBuilder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IFUNCTONBUILDER_H_
-#define IFUNCTONBUILDER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -32,4 +31,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionFactory.h b/Framework/API/inc/MantidAPI/ImplicitFunctionFactory.h
index cf42731a2f4d0406e985707b14905a99c9ffc448..429f6e02d631422b44587d18fd70aff540cf3a21 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionFactory.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMPLICIT_FUNCTION_FACTORY
-#define IMPLICIT_FUNCTION_FACTORY
+#pragma once
 
 /** @class ImplicitFunctionFactory ImplicitFunctionFactory.h
 Kernel/ImplicitFunctionFactory.h
@@ -61,4 +60,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionParameter.h b/Framework/API/inc/MantidAPI/ImplicitFunctionParameter.h
index dd95b4bc98bad3bb8827bda4eb91183dfdc845cd..2559b5e2423aae645f6cc4ac490216b62e8bcb24 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionParameter.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionParameter.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IPARAMETER_H_
-#define IPARAMETER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -138,5 +137,3 @@ template <> struct ElementTraits<float> {
 //------------------------------------------------------------------------------------
 } // namespace API
 } // namespace Mantid
-
-#endif
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParser.h b/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParser.h
index 9e43147192c3e7d1a6fa2ac4b88b504f4daa6911..9acd68eb2f8ae99a23ff1be9fdcf1a79d774b3f3 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParser.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParser.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PARAMETER_PARSER_H_
-#define PARAMETER_PARSER_H_
+#pragma once
 
 /* Used to register classes into the factory. creates a global object in an
  * anonymous namespace. The object itself does nothing, but the comma operator
@@ -81,5 +80,3 @@ protected:
 };
 } // namespace API
 } // namespace Mantid
-
-#endif
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParserFactory.h b/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParserFactory.h
index 05a046a9c6491c92920aeb1ddea489fa13e3c9f2..64619f8ac042e444d93c9f19e86ee20b2a2f9dab 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParserFactory.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionParameterParserFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMPLICIT_FUNCTION_PARAMETER_PARSER_FACTORY_H
-#define IMPLICIT_FUNCTION_PARAMETER_PARSER_FACTORY_H
+#pragma once
 
 /** @class ImplicitFunctionFactory ImplicitFunctionFactory.h
 Kernel/ImplicitFunctionFactory.h
@@ -59,4 +58,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL Mantid::Kernel::SingletonHolder<
 }
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionParser.h b/Framework/API/inc/MantidAPI/ImplicitFunctionParser.h
index 262e35487facf1ada130f33eaa6ace796a03d2f8..f3d1162775e74a804272e2b47f3fecc0f729a2e6 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionParser.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionParser.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTION_ABSTRACT_PARSER_H_
-#define FUNCTION_ABSTRACT_PARSER_H_
+#pragma once
 
 /* Used to register classes into the factory. creates a global object in an
  * anonymous namespace. The object itself does nothing, but the comma operator
@@ -88,4 +87,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/ImplicitFunctionParserFactory.h b/Framework/API/inc/MantidAPI/ImplicitFunctionParserFactory.h
index b485e97cff6cae5cf2fef6fdb8430ebbfd489895..a80b1408401e128a975f79fca95ba15fb59ccaea 100644
--- a/Framework/API/inc/MantidAPI/ImplicitFunctionParserFactory.h
+++ b/Framework/API/inc/MantidAPI/ImplicitFunctionParserFactory.h
@@ -5,8 +5,7 @@
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
 
-#ifndef IMPLICIT_FUNCTION_PARSER_FACTORY
-#define IMPLICIT_FUNCTION_PARSER_FACTORY
+#pragma once
 
 /** @class ImplicitFunctionParserFactory ImplicitFunctionParserFactory.h
    Kernel/ImplicitFunctionParserFactory.h
@@ -63,4 +62,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL Mantid::Kernel::SingletonHolder<
 }
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/IncreasingAxisValidator.h b/Framework/API/inc/MantidAPI/IncreasingAxisValidator.h
index 97866499b58daeaa1c2d25fdb0170ff0ad9362c2..27db54b39dc0f13de4bf3590134617375175acc4 100644
--- a/Framework/API/inc/MantidAPI/IncreasingAxisValidator.h
+++ b/Framework/API/inc/MantidAPI/IncreasingAxisValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INCREASINGAXISVALIDATOR_H_
-#define MANTID_API_INCREASINGAXISVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -31,4 +30,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_INCREASINGAXISVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/IndexProperty.h b/Framework/API/inc/MantidAPI/IndexProperty.h
index c17e0814b923870fd7cd1a9b4ddd3d467f5601fe..e4d3bcfa2e38a2452ba6f733936337eb486996d3 100644
--- a/Framework/API/inc/MantidAPI/IndexProperty.h
+++ b/Framework/API/inc/MantidAPI/IndexProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INDEXPROPERTY_H_
-#define MANTID_API_INDEXPROPERTY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/IWorkspaceProperty.h"
@@ -63,4 +62,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_INDEXPROPERTY_H_ */
diff --git a/Framework/API/inc/MantidAPI/IndexTypeProperty.h b/Framework/API/inc/MantidAPI/IndexTypeProperty.h
index ac03cdeeee8ee589bf07cdd3fbd3f882d6ef8400..830ebf5430e311b3a6ef08820167579a2b8ec5b4 100644
--- a/Framework/API/inc/MantidAPI/IndexTypeProperty.h
+++ b/Framework/API/inc/MantidAPI/IndexTypeProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INDEXTYPEPROPERTY_H_
-#define MANTID_API_INDEXTYPEPROPERTY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/PropertyWithValue.h"
@@ -49,4 +48,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_INDEXTYPEPROPERTY_H_ */
diff --git a/Framework/API/inc/MantidAPI/InstrumentDataService.h b/Framework/API/inc/MantidAPI/InstrumentDataService.h
index 02bbf2548b63dd7bffa0ee9af183031d7a1b3785..07ecdf9ca91e1c5d1dae7ec1eb6d5f356ee4c70c 100644
--- a/Framework/API/inc/MantidAPI/InstrumentDataService.h
+++ b/Framework/API/inc/MantidAPI/InstrumentDataService.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INSTRUMENTDATASERVICE_
-#define MANTID_API_INSTRUMENTDATASERVICE_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidGeometry/Instrument.h"
@@ -46,4 +45,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /*INSTRUMENTDATASERVICE_*/
diff --git a/Framework/API/inc/MantidAPI/InstrumentValidator.h b/Framework/API/inc/MantidAPI/InstrumentValidator.h
index 2e6c916901ec5c101e5df7611ea0e6ef5a356ffc..3953752e4e04240278c832ba2caa4dcdb6d3803e 100644
--- a/Framework/API/inc/MantidAPI/InstrumentValidator.h
+++ b/Framework/API/inc/MantidAPI/InstrumentValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INSTRUMENTVALIDATOR_H_
-#define MANTID_API_INSTRUMENTVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ExperimentInfo.h"
@@ -39,4 +38,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_INSTRUMENTVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/Jacobian.h b/Framework/API/inc/MantidAPI/Jacobian.h
index 779004363df1a8948187cf0739c84cefa6bdada9..44acf84a63e10c19918363389948c6381b4a26e1 100644
--- a/Framework/API/inc/MantidAPI/Jacobian.h
+++ b/Framework/API/inc/MantidAPI/Jacobian.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_JACOBIAN_H_
-#define MANTID_API_JACOBIAN_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -60,4 +59,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_JACOBIAN_H_*/
diff --git a/Framework/API/inc/MantidAPI/JointDomain.h b/Framework/API/inc/MantidAPI/JointDomain.h
index 6b248e396b5cd33bf5963316fc824f05b450b2a0..a9b48f92a37762abdbf1765f35408911b4b3107e 100644
--- a/Framework/API/inc/MantidAPI/JointDomain.h
+++ b/Framework/API/inc/MantidAPI/JointDomain.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_JOINTDOMAIN_H_
-#define MANTID_API_JOINTDOMAIN_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -42,4 +41,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_JOINTDOMAIN_H_*/
diff --git a/Framework/API/inc/MantidAPI/LatticeDomain.h b/Framework/API/inc/MantidAPI/LatticeDomain.h
index 0232181e63d6b34170c4dac17eb648d82354c3a3..62681ac09af3bed9fed85da36f4aafb134977df1 100644
--- a/Framework/API/inc/MantidAPI/LatticeDomain.h
+++ b/Framework/API/inc/MantidAPI/LatticeDomain.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LATTICEDOMAIN_H_
-#define MANTID_API_LATTICEDOMAIN_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/FunctionDomain.h"
@@ -37,4 +36,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_LATTICEDOMAIN_H_ */
diff --git a/Framework/API/inc/MantidAPI/LinearScale.h b/Framework/API/inc/MantidAPI/LinearScale.h
index 4c2084a9e52cb7cb13d8e4105c7f9728552633fe..543c26afafba34c8319e4eeb66bb6ae4b7670e05 100644
--- a/Framework/API/inc/MantidAPI/LinearScale.h
+++ b/Framework/API/inc/MantidAPI/LinearScale.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LINEARSCALE_H_
-#define MANTID_API_LINEARSCALE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -35,4 +34,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_LINEARSCALE_H_*/
diff --git a/Framework/API/inc/MantidAPI/LiveListener.h b/Framework/API/inc/MantidAPI/LiveListener.h
index 1197b7af0569ec3ec9088272e9462d80756c8a3b..74fa6859f53805c2604a2699fcb465b5d1bc81fa 100644
--- a/Framework/API/inc/MantidAPI/LiveListener.h
+++ b/Framework/API/inc/MantidAPI/LiveListener.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LIVELISTENER_H_
-#define MANTID_API_LIVELISTENER_H_
+#pragma once
 
 #include "MantidAPI/ILiveListener.h"
 
@@ -29,4 +28,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_LIVELISTENER_H_ */
diff --git a/Framework/API/inc/MantidAPI/LiveListenerFactory.h b/Framework/API/inc/MantidAPI/LiveListenerFactory.h
index e7e403ad07e6c8227ab45f0b4d624bafc4884942..63d1d0205051aa5882c58a11ad17cb45e0b2a017 100644
--- a/Framework/API/inc/MantidAPI/LiveListenerFactory.h
+++ b/Framework/API/inc/MantidAPI/LiveListenerFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LIVELISTENERFACTORYIMPL_H_
-#define MANTID_API_LIVELISTENERFACTORYIMPL_H_
+#pragma once
 
 /* Used to register unit classes into the factory. creates a global object in an
  * anonymous namespace. The object itself does nothing, but the comma operator
@@ -80,4 +79,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /* MANTID_API_LIVELISTENERFACTORYIMPL_H_ */
diff --git a/Framework/API/inc/MantidAPI/LogFilterGenerator.h b/Framework/API/inc/MantidAPI/LogFilterGenerator.h
index 2a454338a74520deab4e3b8d0f682442b5bf44ae..4b05f4be3bfcc9667182465606897f1cd8796b39 100644
--- a/Framework/API/inc/MantidAPI/LogFilterGenerator.h
+++ b/Framework/API/inc/MantidAPI/LogFilterGenerator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LOGFILTERGENERATOR_H_
-#define MANTID_API_LOGFILTERGENERATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/MatrixWorkspace_fwd.h"
@@ -55,4 +54,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_LOGFILTERGENERATOR_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/LogManager.h b/Framework/API/inc/MantidAPI/LogManager.h
index f1148286640908c10340bf7602a5af85cab21206..925d0963e05b103a9eceaa3dcb209f7c673e29ec 100644
--- a/Framework/API/inc/MantidAPI/LogManager.h
+++ b/Framework/API/inc/MantidAPI/LogManager.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LOGMANAGER_H_
-#define MANTID_API_LOGMANAGER_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/PropertyWithValue.h"
@@ -237,4 +236,3 @@ void LogManager::addProperty(const std::string &name, const TYPE &value,
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_LOGMANAGER_H_
diff --git a/Framework/API/inc/MantidAPI/LogarithmScale.h b/Framework/API/inc/MantidAPI/LogarithmScale.h
index 4cc6c42a968001ccd6fc7b396a6592e62590dd82..9dad793fa630f2a2e973dd8f7721acf0202ff80a 100644
--- a/Framework/API/inc/MantidAPI/LogarithmScale.h
+++ b/Framework/API/inc/MantidAPI/LogarithmScale.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LOGARITHMSCALE_H_
-#define MANTID_API_LOGARITHMSCALE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -42,4 +41,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_LOGARITHMSCALE_H_*/
diff --git a/Framework/API/inc/MantidAPI/MDFrameValidator.h b/Framework/API/inc/MantidAPI/MDFrameValidator.h
index 951a4d27ae1d6f24f6aa5a6f50055a5fc725f8a1..be940b620990882be0c99d3296b5545bb3f43b8a 100644
--- a/Framework/API/inc/MantidAPI/MDFrameValidator.h
+++ b/Framework/API/inc/MantidAPI/MDFrameValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MDFRAMEVALIDATOR_H
-#define MANTID_API_MDFRAMEVALIDATOR_H
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/IMDWorkspace.h"
@@ -37,4 +36,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_MDFRAMEVALIDATOR_H
diff --git a/Framework/API/inc/MantidAPI/MDGeometry.h b/Framework/API/inc/MantidAPI/MDGeometry.h
index f0b429c74953195cf3df90571e3f6df41dcf4bf7..efc9959c027cbf5f39bd57884b6949740734a31b 100644
--- a/Framework/API/inc/MantidAPI/MDGeometry.h
+++ b/Framework/API/inc/MantidAPI/MDGeometry.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MDGEOMETRY_H_
-#define MANTID_API_MDGEOMETRY_H_
+#pragma once
 
 #include "MantidGeometry/MDGeometry/MDTypes.h"
 #include "MantidKernel/Matrix.h"
@@ -168,4 +167,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MDGEOMETRY_H_ */
diff --git a/Framework/API/inc/MantidAPI/MatrixWorkspace.h b/Framework/API/inc/MantidAPI/MatrixWorkspace.h
index e978fc9e06a52805acc1fec931224bf0ed14cd42..149614af973065e24976efe217a8d5c0a3f3e824 100644
--- a/Framework/API/inc/MantidAPI/MatrixWorkspace.h
+++ b/Framework/API/inc/MantidAPI/MatrixWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MATRIXWORKSPACE_H_
-#define MANTID_API_MATRIXWORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ExperimentInfo.h"
@@ -635,4 +634,3 @@ using MatrixWorkspace_const_sptr = boost::shared_ptr<const MatrixWorkspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_MATRIXWORKSPACE_H_*/
diff --git a/Framework/API/inc/MantidAPI/MatrixWorkspaceMDIterator.h b/Framework/API/inc/MantidAPI/MatrixWorkspaceMDIterator.h
index d6d1992de5dcb82b75475a6b31a2b9727963f165..274b983a1d7f2536dcc08360cf614b1b58ffc18f 100644
--- a/Framework/API/inc/MantidAPI/MatrixWorkspaceMDIterator.h
+++ b/Framework/API/inc/MantidAPI/MatrixWorkspaceMDIterator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MATRIXWORKSPACEMDITERATOR_H_
-#define MANTID_API_MATRIXWORKSPACEMDITERATOR_H_
+#pragma once
 
 #include "MantidAPI/IMDIterator.h"
 #include "MantidAPI/MatrixWorkspace_fwd.h"
@@ -134,4 +133,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MATRIXWORKSPACEMDITERATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/MatrixWorkspaceValidator.h b/Framework/API/inc/MantidAPI/MatrixWorkspaceValidator.h
index 991503049937faa987753399115e27a09eb41ab3..ae106c642f35e8d56ba783bad9eaa8aaaff6aafe 100644
--- a/Framework/API/inc/MantidAPI/MatrixWorkspaceValidator.h
+++ b/Framework/API/inc/MantidAPI/MatrixWorkspaceValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MATRIXWORKSPACEVALIDATOR_H_
-#define MANTID_API_MATRIXWORKSPACEVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/MatrixWorkspace.h"
@@ -23,4 +22,3 @@ class MANTID_API_DLL MatrixWorkspaceValidator
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MATRIXWORKSPACEVALIDATOR_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/MatrixWorkspace_fwd.h b/Framework/API/inc/MantidAPI/MatrixWorkspace_fwd.h
index 1efb41896f510787629b4e1d97f2ba91adc92e3f..c81672c25a7d50ea0a3010ab5799451d58a695e2 100644
--- a/Framework/API/inc/MantidAPI/MatrixWorkspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/MatrixWorkspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MATRIXWORKSPACE_FWD_H_
-#define MANTID_API_MATRIXWORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -30,4 +29,3 @@ using MatrixWorkspace_const_uptr = std::unique_ptr<const MatrixWorkspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_MATRIXWORKSPACE_FWD_H_
diff --git a/Framework/API/inc/MantidAPI/MuParserUtils.h b/Framework/API/inc/MantidAPI/MuParserUtils.h
index da0cb80466c8f61f5ab2ea1bacf754cf1886bb04..02f7ecd3e5a0b6c4b6f8f9723d7a6c50b47279c7 100644
--- a/Framework/API/inc/MantidAPI/MuParserUtils.h
+++ b/Framework/API/inc/MantidAPI/MuParserUtils.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MUPARSERUTILS_H_
-#define MANTID_API_MUPARSERUTILS_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -37,4 +36,3 @@ void MANTID_API_DLL extraOneVarFunctions(mu::Parser &parser);
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MUPARSERUTILS_H_ */
diff --git a/Framework/API/inc/MantidAPI/MultiDomainFunction.h b/Framework/API/inc/MantidAPI/MultiDomainFunction.h
index 85ed522428e7dc3cdc4c6cbf1f01b1517f78dce1..3311dcd26f4c4039167fac346c374820259762df 100644
--- a/Framework/API/inc/MantidAPI/MultiDomainFunction.h
+++ b/Framework/API/inc/MantidAPI/MultiDomainFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIDOMAINFUNCTION_H_
-#define MANTID_API_MULTIDOMAINFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -101,4 +100,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_MULTIDOMAINFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/MultiPeriodGroupAlgorithm.h b/Framework/API/inc/MantidAPI/MultiPeriodGroupAlgorithm.h
index 616836dcb7c163fbf688edc0289791a3e45d125f..d222f89e4815854c693af4701757ded9b471d019 100644
--- a/Framework/API/inc/MantidAPI/MultiPeriodGroupAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/MultiPeriodGroupAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MUTLIPERIODGROUPALGORITHM_H_
-#define MANTID_API_MUTLIPERIODGROUPALGORITHM_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/MultiPeriodGroupWorker.h"
@@ -47,4 +46,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MUTLIPERIODGROUPALGORITHM_H_ */
diff --git a/Framework/API/inc/MantidAPI/MultiPeriodGroupWorker.h b/Framework/API/inc/MantidAPI/MultiPeriodGroupWorker.h
index 87bc088c1ec8d0a238cdfcf55a8cafcee1357cb3..ff9debdd054dca49f634b5acd76a23df5718074a 100644
--- a/Framework/API/inc/MantidAPI/MultiPeriodGroupWorker.h
+++ b/Framework/API/inc/MantidAPI/MultiPeriodGroupWorker.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIPERIODGROUPWORKER_H_
-#define MANTID_API_MULTIPERIODGROUPWORKER_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/WorkspaceGroup_fwd.h"
@@ -77,4 +76,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MULTIPERIODGROUPWORKER_H_ */
diff --git a/Framework/API/inc/MantidAPI/MultipleExperimentInfos.h b/Framework/API/inc/MantidAPI/MultipleExperimentInfos.h
index 91a4a02b96ec8d8215b9a82c5d158dbc00ed3690..0a0fbe4e9c394a493e585461c230847ca005fc21 100644
--- a/Framework/API/inc/MantidAPI/MultipleExperimentInfos.h
+++ b/Framework/API/inc/MantidAPI/MultipleExperimentInfos.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIPLEEXPERIMENTINFOS_H_
-#define MANTID_API_MULTIPLEEXPERIMENTINFOS_H_
+#pragma once
 
 #include "MantidAPI/ExperimentInfo.h"
 #include "MantidKernel/System.h"
@@ -55,4 +54,3 @@ using MultipleExperimentInfos_const_sptr =
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MULTIPLEEXPERIMENTINFOS_H_ */
diff --git a/Framework/API/inc/MantidAPI/MultipleFileProperty.h b/Framework/API/inc/MantidAPI/MultipleFileProperty.h
index 06df859311dd68006d788b0100832737aa98d246..a91825315e3af497de57d7067c6a510800495454 100644
--- a/Framework/API/inc/MantidAPI/MultipleFileProperty.h
+++ b/Framework/API/inc/MantidAPI/MultipleFileProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIPLEFILEPROPERTY_H_
-#define MANTID_API_MULTIPLEFILEPROPERTY_H_
+#pragma once
 
 #include "MantidKernel/MultiFileNameParser.h"
 #include "MantidKernel/PropertyWithValue.h"
@@ -175,4 +174,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_MULTIPLEFILEPROPERTY_H_ */
diff --git a/Framework/API/inc/MantidAPI/NotebookBuilder.h b/Framework/API/inc/MantidAPI/NotebookBuilder.h
index 95294f65f41b7789729bd2b98892c5f52c3432e0..304dd33296f581b5767c4a0faf8c0af389d36c5d 100644
--- a/Framework/API/inc/MantidAPI/NotebookBuilder.h
+++ b/Framework/API/inc/MantidAPI/NotebookBuilder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_NOTEBOOKBUILDER_H_
-#define MANTID_API_NOTEBOOKBUILDER_H_
+#pragma once
 
 /** @class NotebookBuilder
 
@@ -51,4 +50,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_NOTEBOOKBUILDER_H_*/
diff --git a/Framework/API/inc/MantidAPI/NotebookWriter.h b/Framework/API/inc/MantidAPI/NotebookWriter.h
index cc81a195ba0cf3f2f2b976ce53f2d0019c53fe01..2593ef14d240d7d270e12328788cf0978e79d569 100644
--- a/Framework/API/inc/MantidAPI/NotebookWriter.h
+++ b/Framework/API/inc/MantidAPI/NotebookWriter.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NOTEBOOKWRITER_H
-#define MANTID_NOTEBOOKWRITER_H
+#pragma once
 
 /** @class NotebookWriter
 
@@ -43,4 +42,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_NOTEBOOKWRITER_H
diff --git a/Framework/API/inc/MantidAPI/NullCoordTransform.h b/Framework/API/inc/MantidAPI/NullCoordTransform.h
index 7a5f1a4dc28aa5f6abc3ea2126e2cc6a8a9873db..59e8e7c292f89bcc34666f86cd96f2fc136aaa03 100644
--- a/Framework/API/inc/MantidAPI/NullCoordTransform.h
+++ b/Framework/API/inc/MantidAPI/NullCoordTransform.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDAPI_NULLCOORDTRANSFORM_H
-#define MANTIDAPI_NULLCOORDTRANSFORM_H
+#pragma once
 
 #include "MantidAPI/CoordTransform.h"
 
@@ -34,4 +33,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/NumericAxis.h b/Framework/API/inc/MantidAPI/NumericAxis.h
index db1e4d0ccf0882c55d60cfe512bc3e5517371f44..886cb299e4e9a2034fd498e666ed77de66fed08c 100644
--- a/Framework/API/inc/MantidAPI/NumericAxis.h
+++ b/Framework/API/inc/MantidAPI/NumericAxis.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_NUMERICAXIS_H_
-#define MANTID_API_NUMERICAXIS_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -72,4 +71,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_NUMERICAXIS_H_ */
diff --git a/Framework/API/inc/MantidAPI/NumericAxisValidator.h b/Framework/API/inc/MantidAPI/NumericAxisValidator.h
index a228afbd370ec4f5c1a9674d8d60df202a70bc54..df97ba9bbfb788b1a06ac88ee83c830112fc3fab 100644
--- a/Framework/API/inc/MantidAPI/NumericAxisValidator.h
+++ b/Framework/API/inc/MantidAPI/NumericAxisValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_NUMERICAXISVALIDATOR_H_
-#define MANTID_API_NUMERICAXISVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -35,4 +34,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_NUMERICAXISVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/OrientedLatticeValidator.h b/Framework/API/inc/MantidAPI/OrientedLatticeValidator.h
index d890c68fe9d22450ad6550e87b0c9392bf4269b5..f6bae5966b5380377234d8916f769ca46484c009 100644
--- a/Framework/API/inc/MantidAPI/OrientedLatticeValidator.h
+++ b/Framework/API/inc/MantidAPI/OrientedLatticeValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ORIENTEDLATTICEVALIDATOR_H
-#define MANTID_API_ORIENTEDLATTICEVALIDATOR_H
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ExperimentInfo.h"
@@ -34,4 +33,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_ORIENTEDLATTICEVALIDATOR_H
diff --git a/Framework/API/inc/MantidAPI/ParallelAlgorithm.h b/Framework/API/inc/MantidAPI/ParallelAlgorithm.h
index 7c52fcfb3596ba663b281ab84a8eaf51ce507e61..8d6be0ee81fa404decb928a33bfb0bfb4924fa7b 100644
--- a/Framework/API/inc/MantidAPI/ParallelAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/ParallelAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PARALLELALGORITHM_H_
-#define MANTID_API_PARALLELALGORITHM_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/DllConfig.h"
@@ -40,4 +39,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_PARALLELALGORITHM_H_ */
diff --git a/Framework/API/inc/MantidAPI/ParamFunction.h b/Framework/API/inc/MantidAPI/ParamFunction.h
index 78be03e458073dd11e9de003c1f6604daa568beb..615f5e6b2461f808ebb4d2dafa082529c2f3b8b4 100644
--- a/Framework/API/inc/MantidAPI/ParamFunction.h
+++ b/Framework/API/inc/MantidAPI/ParamFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PARAMFUNCTION_H_
-#define MANTID_API_PARAMFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -116,4 +115,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_PARAMFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/ParameterReference.h b/Framework/API/inc/MantidAPI/ParameterReference.h
index 2689db24760a4be8c5571179a6d1db0a880183c4..e0995261d44deb9213e93719ad99d1a231e30dd3 100644
--- a/Framework/API/inc/MantidAPI/ParameterReference.h
+++ b/Framework/API/inc/MantidAPI/ParameterReference.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PARAMETERREFERENCE_H_
-#define MANTID_API_PARAMETERREFERENCE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -58,4 +57,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_PARAMETERREFERENCE_H_*/
diff --git a/Framework/API/inc/MantidAPI/ParameterTie.h b/Framework/API/inc/MantidAPI/ParameterTie.h
index a0c51c7fbee7ec60a3f0f1eb39d476b69f60e67d..4134ea15686c3fb273fb4d15d13215f95dfa120a 100644
--- a/Framework/API/inc/MantidAPI/ParameterTie.h
+++ b/Framework/API/inc/MantidAPI/ParameterTie.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PARAMETERTIE_H_
-#define MANTID_API_PARAMETERTIE_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -73,4 +72,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_PARAMETERTIE_H_*/
diff --git a/Framework/API/inc/MantidAPI/PeakFunctionIntegrator.h b/Framework/API/inc/MantidAPI/PeakFunctionIntegrator.h
index e9c0ea481af45efb54871ab44b7ddbd13f2367ba..5baf433fe0ae0e1733b10d47e4230c8d62887c64 100644
--- a/Framework/API/inc/MantidAPI/PeakFunctionIntegrator.h
+++ b/Framework/API/inc/MantidAPI/PeakFunctionIntegrator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PEAKFUNCTIONINTEGRATOR_H
-#define PEAKFUNCTIONINTEGRATOR_H
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/IPeakFunction.h"
@@ -64,4 +63,3 @@ double MANTID_API_DLL gsl_peak_wrapper(double x, void *parameters);
 } // namespace API
 } // namespace Mantid
 
-#endif // PEAKFUNCTIONINTEGRATOR_H
diff --git a/Framework/API/inc/MantidAPI/PrecompiledHeader.h b/Framework/API/inc/MantidAPI/PrecompiledHeader.h
index 377951c4427176403ad49c0d45f134b059d5ed08..01f2a9561a1bb07677870419e8d5eca3000c5bde 100644
--- a/Framework/API/inc/MantidAPI/PrecompiledHeader.h
+++ b/Framework/API/inc/MantidAPI/PrecompiledHeader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PRECOMPILED_HEADER_H_
-#define MANTID_API_PRECOMPILED_HEADER_H_
+#pragma once
 
 // Mantid
 #include "MantidGeometry/IComponent.h"
@@ -39,4 +38,3 @@
 #include <Poco/DOM/DOMParser.h>
 #include <Poco/XML/XML.h>
 
-#endif // MANTID_API_PRECOMPILED_HEADER_H_
diff --git a/Framework/API/inc/MantidAPI/Progress.h b/Framework/API/inc/MantidAPI/Progress.h
index 9f9547c04348afc3689712c69b5ca024374dba97..5c16e6fd4177f684719b7ae6d78685c891231728 100644
--- a/Framework/API/inc/MantidAPI/Progress.h
+++ b/Framework/API/inc/MantidAPI/Progress.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PROGRESS_H_
-#define MANTID_API_PROGRESS_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -41,4 +40,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_PROGRESS_H_*/
diff --git a/Framework/API/inc/MantidAPI/Projection.h b/Framework/API/inc/MantidAPI/Projection.h
index 7f44c118df1d253cb55e21f9d0790fe72405a2f5..f5ac34462cd858c240c5b49b56f8ac996317f69f 100644
--- a/Framework/API/inc/MantidAPI/Projection.h
+++ b/Framework/API/inc/MantidAPI/Projection.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PROJECTION_H_
-#define MANTID_API_PROJECTION_H_
+#pragma once
 
 #include "MantidAPI/ITableWorkspace_fwd.h"
 #include "MantidKernel/V3D.h"
@@ -72,4 +71,3 @@ using Projection_sptr = boost::shared_ptr<Projection>;
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_PROJECTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/RawCountValidator.h b/Framework/API/inc/MantidAPI/RawCountValidator.h
index 91480d9726cf8d115488f6339c99210e42bfbe3f..e994fce1c69cc3f94d6a5174318448d1a7c121dd 100644
--- a/Framework/API/inc/MantidAPI/RawCountValidator.h
+++ b/Framework/API/inc/MantidAPI/RawCountValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_RAWCOUNTVALIDATOR_H_
-#define MANTID_API_RAWCOUNTVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -35,4 +34,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_RAWCOUNTVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/RefAxis.h b/Framework/API/inc/MantidAPI/RefAxis.h
index 241ea7ab14e5ed4b3ce9ce52becd628cfb63d22e..9d1c8926ccf13bce4f55ed5c87153ed8c309e2ce 100644
--- a/Framework/API/inc/MantidAPI/RefAxis.h
+++ b/Framework/API/inc/MantidAPI/RefAxis.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_REFAXIS_H_
-#define MANTID_API_REFAXIS_H_
+#pragma once
 
 #include "MantidAPI/NumericAxis.h"
 
@@ -58,4 +57,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_REFAXIS_H_*/
diff --git a/Framework/API/inc/MantidAPI/RegisterFileLoader.h b/Framework/API/inc/MantidAPI/RegisterFileLoader.h
index cc2cad79b6f204e8d51a787efad94a8e8d63ac7d..74396f2b1cbc897df4c91651d8573f6d4ab5c70a 100644
--- a/Framework/API/inc/MantidAPI/RegisterFileLoader.h
+++ b/Framework/API/inc/MantidAPI/RegisterFileLoader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_REGISTERFILELOADER_H_
-#define MANTID_API_REGISTERFILELOADER_H_
+#pragma once
 
 #include "MantidAPI/FileLoaderRegistry.h"
 
@@ -40,4 +39,3 @@
        0));                                                                    \
   }
 
-#endif /* MANTID_API_REGISTERFILELOADER_H_ */
diff --git a/Framework/API/inc/MantidAPI/RemoteJobManagerFactory.h b/Framework/API/inc/MantidAPI/RemoteJobManagerFactory.h
index 72174946adc2a6c8aa71d75c6879619a5deb8860..d8d2f4074695c38ca9453e3521a073dc597f9362 100644
--- a/Framework/API/inc/MantidAPI/RemoteJobManagerFactory.h
+++ b/Framework/API/inc/MantidAPI/RemoteJobManagerFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_REMOTEJOBMANAGERFACTORY_H_
-#define MANTID_API_REMOTEJOBMANAGERFACTORY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/IRemoteJobManager.h"
@@ -99,4 +98,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
        0));                                                                    \
   }
 
-#endif // MANTID_API_REMOTEJOBMANAGERFACTORY_H_
diff --git a/Framework/API/inc/MantidAPI/ResizeRectangularDetectorHelper.h b/Framework/API/inc/MantidAPI/ResizeRectangularDetectorHelper.h
index 9cbf6445c00e500b2409ce78d6811453d202dcf1..5d9095ab28a93a6c82f1878a5338366b31bc44da 100644
--- a/Framework/API/inc/MantidAPI/ResizeRectangularDetectorHelper.h
+++ b/Framework/API/inc/MantidAPI/ResizeRectangularDetectorHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_RESIZERECTANGULARDETECTORHELPER_H_
-#define MANTID_API_RESIZERECTANGULARDETECTORHELPER_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -23,4 +22,3 @@ MANTID_API_DLL void applyRectangularDetectorScaleToComponentInfo(
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_RESIZERECTANGULARDETECTORHELPER_H_ */
diff --git a/Framework/API/inc/MantidAPI/Run.h b/Framework/API/inc/MantidAPI/Run.h
index bec42de7544484f783a752eb14a5018097ab8ea7..979f650069f9ca207cea560589afe268833a23b4 100644
--- a/Framework/API/inc/MantidAPI/Run.h
+++ b/Framework/API/inc/MantidAPI/Run.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_RUN_H_
-#define MANTID_API_RUN_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/LogManager.h"
@@ -111,4 +110,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTIDAPI_RUN_H_
diff --git a/Framework/API/inc/MantidAPI/Sample.h b/Framework/API/inc/MantidAPI/Sample.h
index 38eac2a75d2848ba9a6c666d442b831468a54017..247d2a70be207a02199c392df638a4a1fd3043c8 100644
--- a/Framework/API/inc/MantidAPI/Sample.h
+++ b/Framework/API/inc/MantidAPI/Sample.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SAMPLE_H_
-#define MANTID_API_SAMPLE_H_
+#pragma once
 
 //-----------------------------------------------------------------------------
 // Includes
@@ -146,4 +145,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_SAMPLE_H_*/
diff --git a/Framework/API/inc/MantidAPI/SampleShapeValidator.h b/Framework/API/inc/MantidAPI/SampleShapeValidator.h
index 6a62d3b33cbac8c13e22d3e1e28e4c7c32fddcdd..aea1ce66a63ff8c9d91c1ea1ae0b757fdeff303e 100644
--- a/Framework/API/inc/MantidAPI/SampleShapeValidator.h
+++ b/Framework/API/inc/MantidAPI/SampleShapeValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SAMPLESHAPEVALIDATOR_H_
-#define MANTID_API_SAMPLESHAPEVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/ExperimentInfo.h"
@@ -32,4 +31,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SAMPLESHAPEVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/SampleValidator.h b/Framework/API/inc/MantidAPI/SampleValidator.h
index 3c8219b47e439490e61b3e9237afcfd3ff8e3106..3dd9e4d9eb391f9c3c07412375ebd730e6b0e48c 100644
--- a/Framework/API/inc/MantidAPI/SampleValidator.h
+++ b/Framework/API/inc/MantidAPI/SampleValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SAMPLEVALIDATOR_H_
-#define MANTID_API_SAMPLEVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -32,4 +31,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SAMPLEVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/ScopedWorkspace.h b/Framework/API/inc/MantidAPI/ScopedWorkspace.h
index da4d2ac7f17b51f7fd68a6b794452207c0e97c82..fef0b39bbf916cfa443d3865e77299aec3aa94ce 100644
--- a/Framework/API/inc/MantidAPI/ScopedWorkspace.h
+++ b/Framework/API/inc/MantidAPI/ScopedWorkspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SCOPEDWORKSPACE_H_
-#define MANTID_API_SCOPEDWORKSPACE_H_
+#pragma once
 
 #include <string>
 
@@ -80,4 +79,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SCOPEDWORKSPACE_H_ */
diff --git a/Framework/API/inc/MantidAPI/ScriptBuilder.h b/Framework/API/inc/MantidAPI/ScriptBuilder.h
index aca6c314b76cc936d5914da3aafbf3a81a691faf..379f253b7dd7c293a85f85e327d343f382376a8d 100644
--- a/Framework/API/inc/MantidAPI/ScriptBuilder.h
+++ b/Framework/API/inc/MantidAPI/ScriptBuilder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SCRIPTBUILDER_H_
-#define MANTID_API_SCRIPTBUILDER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -69,4 +68,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_SCRIPTBUILDER_H_*/
diff --git a/Framework/API/inc/MantidAPI/ScriptRepository.h b/Framework/API/inc/MantidAPI/ScriptRepository.h
index 5a4535e34120c831e0364d71dc05de1c84ec4c6b..84e0ffd47250f213ac56bbd47a4d96177cc37554 100644
--- a/Framework/API/inc/MantidAPI/ScriptRepository.h
+++ b/Framework/API/inc/MantidAPI/ScriptRepository.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SCRIPTREPOSITORY_H_
-#define MANTID_API_SCRIPTREPOSITORY_H_
+#pragma once
 
 #include <string>
 #include <vector>
@@ -594,4 +593,3 @@ using ScriptRepository_sptr = boost::shared_ptr<ScriptRepository>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_SCRIPTREPOSITORY_H_
diff --git a/Framework/API/inc/MantidAPI/ScriptRepositoryFactory.h b/Framework/API/inc/MantidAPI/ScriptRepositoryFactory.h
index 9a9cc6fd3de1a2f3af404688ecf40b1b31e326cc..a4c67415734d5887edbf51371d667834c22a2a09 100644
--- a/Framework/API/inc/MantidAPI/ScriptRepositoryFactory.h
+++ b/Framework/API/inc/MantidAPI/ScriptRepositoryFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SCRIPTREPOSITORYFACTORY_H_
-#define MANTID_API_SCRIPTREPOSITORYFACTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -78,4 +77,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
        0));                                                                    \
   }
 
-#endif /*MANTID_API_SCRIPTREPOSITORYFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/SerialAlgorithm.h b/Framework/API/inc/MantidAPI/SerialAlgorithm.h
index c21d91298c2525cf617a1b43b8781039051c65d8..9e0a3af618dd587f7e37fef7f3e596c0f2512cf0 100644
--- a/Framework/API/inc/MantidAPI/SerialAlgorithm.h
+++ b/Framework/API/inc/MantidAPI/SerialAlgorithm.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SERIALALGORITHM_H_
-#define MANTID_API_SERIALALGORITHM_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/DllConfig.h"
@@ -42,4 +41,3 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SERIALALGORITHM_H_ */
diff --git a/Framework/API/inc/MantidAPI/SingleCountValidator.h b/Framework/API/inc/MantidAPI/SingleCountValidator.h
index 0c3909f2544595db1746cd6b646e64d12bbd8cde..35403427fdc094be6f3145dccc87088e4291795d 100644
--- a/Framework/API/inc/MantidAPI/SingleCountValidator.h
+++ b/Framework/API/inc/MantidAPI/SingleCountValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SINGLECOUNTVALIDATOR_H_
-#define MANTID_API_SINGLECOUNTVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -37,4 +36,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SINGLECOUNTVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/SingleValueParameter.h b/Framework/API/inc/MantidAPI/SingleValueParameter.h
index 30cc781cca6e3a7adab92a6a7fa3097c84815d0f..b91c7750b73d4d84c4e125bba186e06301fdb3fe 100644
--- a/Framework/API/inc/MantidAPI/SingleValueParameter.h
+++ b/Framework/API/inc/MantidAPI/SingleValueParameter.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_MDALGORITHMS_SingleValueParameter_H_
-#define MANTID_MDALGORITHMS_SingleValueParameter_H_
+#pragma once
 
 #include "MantidAPI/ImplicitFunctionParameter.h"
 #include "MantidKernel/System.h"
@@ -153,5 +152,3 @@ std::string SingleValueParameter<Derived, ValType>::toXMLString() const {
   };
 } // namespace API
 } // namespace Mantid
-
-#endif
diff --git a/Framework/API/inc/MantidAPI/SingleValueParameterParser.h b/Framework/API/inc/MantidAPI/SingleValueParameterParser.h
index 22db7d22958367c408154e4d56ade669bfcf4117..dd43b5b93d3773fd03aff6288d3da41929b762f2 100644
--- a/Framework/API/inc/MantidAPI/SingleValueParameterParser.h
+++ b/Framework/API/inc/MantidAPI/SingleValueParameterParser.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef SINGLE_VALUE_PARAMETER_PARSER_H_
-#define SINGLE_VALUE_PARAMETER_PARSER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -112,5 +111,3 @@ void SingleValueParameterParser<SingleValueParameterType>::setSuccessorParser(
 }
 } // namespace API
 } // namespace Mantid
-
-#endif
diff --git a/Framework/API/inc/MantidAPI/SpectraAxis.h b/Framework/API/inc/MantidAPI/SpectraAxis.h
index 8b8f1c5cf3c24e1a6a3860c104c4747d85541561..53cc306ed8309d21bb611877898cef86724599f9 100644
--- a/Framework/API/inc/MantidAPI/SpectraAxis.h
+++ b/Framework/API/inc/MantidAPI/SpectraAxis.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRAAXIS_H_
-#define MANTID_API_SPECTRAAXIS_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -70,4 +69,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SpectraAxis_H_ */
diff --git a/Framework/API/inc/MantidAPI/SpectraAxisValidator.h b/Framework/API/inc/MantidAPI/SpectraAxisValidator.h
index b73eeb29a9a0d81d87d5ac0f09dffe5a37ff510f..6b32a5ec0720fbbf6b8369d0e336b1e91c7b1e2d 100644
--- a/Framework/API/inc/MantidAPI/SpectraAxisValidator.h
+++ b/Framework/API/inc/MantidAPI/SpectraAxisValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRAAXISVALIDATOR_H_
-#define MANTID_API_SPECTRAAXISVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -35,4 +34,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SPECTRAAXISVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/SpectraDetectorTypes.h b/Framework/API/inc/MantidAPI/SpectraDetectorTypes.h
index 8b5fdac3065a6f766667ab0394646424860f711f..226a64cb6b3bed2e2c4f18b1a5ef94a799da39a1 100644
--- a/Framework/API/inc/MantidAPI/SpectraDetectorTypes.h
+++ b/Framework/API/inc/MantidAPI/SpectraDetectorTypes.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRADETECTORMAP_TYPES
-#define MANTID_API_SPECTRADETECTORMAP_TYPES
+#pragma once
 //------------------------------------------------------------------------------
 // Includes
 //------------------------------------------------------------------------------
@@ -23,4 +22,3 @@ using detid2index_map = std::unordered_map<detid_t, size_t>;
 using det2group_map = std::unordered_map<detid_t, std::set<detid_t>>;
 } // namespace Mantid
 
-#endif // MANTID_API_SPECTRADETECTORMAP_TYPES
diff --git a/Framework/API/inc/MantidAPI/SpectrumDetectorMapping.h b/Framework/API/inc/MantidAPI/SpectrumDetectorMapping.h
index 26ecd29a26757e6329f16981ee00b3085773985a..3f6847d3f3ccc60a07599d6a0840f2eef57d997c 100644
--- a/Framework/API/inc/MantidAPI/SpectrumDetectorMapping.h
+++ b/Framework/API/inc/MantidAPI/SpectrumDetectorMapping.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRUMDETECTORMAPPING_H_
-#define MANTID_API_SPECTRUMDETECTORMAPPING_H_
+#pragma once
 
 #include <set>
 #include <vector>
@@ -67,5 +66,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /* MANTID_API_SPECTRUMDETECTORMAPPING_H_ */
diff --git a/Framework/API/inc/MantidAPI/SpectrumInfo.h b/Framework/API/inc/MantidAPI/SpectrumInfo.h
index 359b361aa59b730039ec84d4f49112ae9625fba3..926a6c944986c169a3a2c8c8fb87da5c1c06c124 100644
--- a/Framework/API/inc/MantidAPI/SpectrumInfo.h
+++ b/Framework/API/inc/MantidAPI/SpectrumInfo.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRUMINFO_H_
-#define MANTID_API_SPECTRUMINFO_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/SpectrumInfoIterator.h"
@@ -111,4 +110,3 @@ using SpectrumInfoConstIt = SpectrumInfoIterator<const SpectrumInfo>;
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SPECTRUMINFO_H_ */
diff --git a/Framework/API/inc/MantidAPI/SpectrumInfoItem.h b/Framework/API/inc/MantidAPI/SpectrumInfoItem.h
index 29ac3b3c900c3d0b0aaeb090db7763b2a586759b..a743e1f011688b42e5f4c31fe7be5ad696ecc245 100644
--- a/Framework/API/inc/MantidAPI/SpectrumInfoItem.h
+++ b/Framework/API/inc/MantidAPI/SpectrumInfoItem.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRUMINFOITEM_H_
-#define MANTID_API_SPECTRUMINFOITEM_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/V3D.h"
@@ -80,4 +79,3 @@ public:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SPECTRUMINFOITEM_H_ */
diff --git a/Framework/API/inc/MantidAPI/SpectrumInfoIterator.h b/Framework/API/inc/MantidAPI/SpectrumInfoIterator.h
index 6cb8b133be0359861e5f16610ea90c18d21e1295..f3370579b61f8e53ceffa1ffca7fa30824fc1c42 100644
--- a/Framework/API/inc/MantidAPI/SpectrumInfoIterator.h
+++ b/Framework/API/inc/MantidAPI/SpectrumInfoIterator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRUMINFOITERATOR_H_
-#define MANTID_API_SPECTRUMINFOITERATOR_H_
+#pragma once
 
 #include "MantidAPI/SpectrumInfoItem.h"
 #include <boost/iterator/iterator_facade.hpp>
@@ -86,4 +85,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_SPECTRUMINFOITERATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/TableRow.h b/Framework/API/inc/MantidAPI/TableRow.h
index a53f979eaed0a6b2108400b1aca827aa765aef2f..f3096148507b0dfb569e16ea2304c870de00b625 100644
--- a/Framework/API/inc/MantidAPI/TableRow.h
+++ b/Framework/API/inc/MantidAPI/TableRow.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_TABLEROW_H_
-#define MANTID_API_TABLEROW_H_
+#pragma once
 
 #include "MantidAPI/Column.h"
 
@@ -170,5 +169,3 @@ MANTID_API_DLL std::ostream &operator<<(std::ostream &s, const TableRow &row);
 
 } // namespace API
 } // namespace Mantid
-
-#endif /*  MANTID_API_TABLEROW_H_ */
diff --git a/Framework/API/inc/MantidAPI/TempFunction.h b/Framework/API/inc/MantidAPI/TempFunction.h
index 1feae331a472b0da5f09237bc316488d77bb0e76..f5c1346a93810fbe96cc32ca4702fac6481dd800 100644
--- a/Framework/API/inc/MantidAPI/TempFunction.h
+++ b/Framework/API/inc/MantidAPI/TempFunction.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_TEMPFUNCTION_H_
-#define MANTID_API_TEMPFUNCTION_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -16,7 +15,6 @@
 
 #ifdef _WIN32
 #pragma warning(disable : 4250)
-#endif
 
 namespace Mantid {
 namespace API {
@@ -204,4 +202,4 @@ protected:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_TEMPFUNCTION_H_*/
+ /*MANTID_API_TEMPFUNCTION_H_*/
diff --git a/Framework/API/inc/MantidAPI/TextAxis.h b/Framework/API/inc/MantidAPI/TextAxis.h
index 634aabd22084cd5423473f40a5ed863dc8ad806d..b4d3838fe76b9967c28baccd1b6d06053d8fb4f2 100644
--- a/Framework/API/inc/MantidAPI/TextAxis.h
+++ b/Framework/API/inc/MantidAPI/TextAxis.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_TEXTAXIS_H_
-#define MANTID_API_TEXTAXIS_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -69,5 +68,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif /* MANTID_API_TEXTAXIS_H_ */
diff --git a/Framework/API/inc/MantidAPI/TransformScaleFactory.h b/Framework/API/inc/MantidAPI/TransformScaleFactory.h
index 33693f24c7b7c301182fccdceba36a42eabb72c8..a4353cf256a8e5c755bf4868e70bcb55efb859a2 100644
--- a/Framework/API/inc/MantidAPI/TransformScaleFactory.h
+++ b/Framework/API/inc/MantidAPI/TransformScaleFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_TRANSFORMSCALEFACTORY_H_
-#define MANTID_API_TRANSFORMSCALEFACTORY_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidKernel/DynamicFactory.h"
@@ -64,4 +63,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
 }
 } // namespace Mantid
 
-#endif /* MANTID_API_TRANSFORMSCALEFACTORY_H_ */
diff --git a/Framework/API/inc/MantidAPI/VectorParameter.h b/Framework/API/inc/MantidAPI/VectorParameter.h
index 22734b9e1c7623cdea254693c827bac7389efdf3..aa4c69e0e80b22d7aa321454ac2d1769e99905fb 100644
--- a/Framework/API/inc/MantidAPI/VectorParameter.h
+++ b/Framework/API/inc/MantidAPI/VectorParameter.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_MDALGORITHMS_VectorParameter_H_
-#define MANTID_MDALGORITHMS_VectorParameter_H_
+#pragma once
 
 #include "MantidAPI/ImplicitFunctionParameter.h"
 #include "MantidKernel/System.h"
@@ -240,4 +239,3 @@ ElemType &VectorParameter<Derived, ElemType>::at(size_t index) {
 } // namespace API
 } // namespace Mantid
 
-#endif
diff --git a/Framework/API/inc/MantidAPI/VectorParameterParser.h b/Framework/API/inc/MantidAPI/VectorParameterParser.h
index d0947fcbfa47f618db0f29375618d000c9aac5b4..fd158e4153ba4c7e21fdeb7d7b174bc59f7e1115 100644
--- a/Framework/API/inc/MantidAPI/VectorParameterParser.h
+++ b/Framework/API/inc/MantidAPI/VectorParameterParser.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef VECTOR_VALUE_PARAMETER_PARSER_H_
-#define VECTOR_VALUE_PARAMETER_PARSER_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -132,5 +131,3 @@ void VectorParameterParser<VectorValueParameterType>::setSuccessorParser(
 }
 } // namespace API
 } // namespace Mantid
-
-#endif
diff --git a/Framework/API/inc/MantidAPI/Workspace.h b/Framework/API/inc/MantidAPI/Workspace.h
index af1a968a2ce52e84e943da39c3fd089b362abe83..d4bafe889ef92ba79a40aa3e3512d8f9c924d23f 100644
--- a/Framework/API/inc/MantidAPI/Workspace.h
+++ b/Framework/API/inc/MantidAPI/Workspace.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACE_H_
-#define MANTID_API_WORKSPACE_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/Workspace_fwd.h"
@@ -118,4 +117,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_WORKSPACE_H_*/
diff --git a/Framework/API/inc/MantidAPI/WorkspaceFactory.h b/Framework/API/inc/MantidAPI/WorkspaceFactory.h
index b3847501f74b9bf9244ffe6af4de2ebf0001c3c6..b8e2719ed89adda215f2d2f3be6945ab6c2774e7 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceFactory.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_KERNEL_WORKSPACEFACTORY_H_
-#define MANTID_KERNEL_WORKSPACEFACTORY_H_
+#pragma once
 
 /* Used to register classes into the factory. creates a global object in an
  * anonymous namespace. The object itself does nothing, but the comma operator
@@ -98,5 +97,3 @@ EXTERN_MANTID_API template class MANTID_API_DLL
     Mantid::Kernel::SingletonHolder<Mantid::API::WorkspaceFactoryImpl>;
 }
 } // namespace Mantid
-
-#endif /*MANTID_KERNEL_WORKSPACEFACTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/WorkspaceGroup.h b/Framework/API/inc/MantidAPI/WorkspaceGroup.h
index c10e7fa5953fcdac04a03e72f8b9f1c7afbd0932..bc63d5e9b5954709e5dcca20275ee06ab812b89c 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceGroup.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceGroup.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEGROUP_H
-#define MANTID_API_WORKSPACEGROUP_H
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -170,4 +169,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_WORKSPACEGROUP_H*/
diff --git a/Framework/API/inc/MantidAPI/WorkspaceGroup_fwd.h b/Framework/API/inc/MantidAPI/WorkspaceGroup_fwd.h
index f435fd36314fbb0b705c96c354b04f3ac7b5eb45..e70645159a41bb42297a7244a6c862ee53978274 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceGroup_fwd.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceGroup_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEGROUP_FWD_H_
-#define MANTID_API_WORKSPACEGROUP_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -30,4 +29,3 @@ using WorkspaceGroup_const_uptr = std::unique_ptr<const WorkspaceGroup>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_WORKSPACEGROUP_FWD_H_
diff --git a/Framework/API/inc/MantidAPI/WorkspaceHasDxValidator.h b/Framework/API/inc/MantidAPI/WorkspaceHasDxValidator.h
index e1d9570ac26bd9bcc6ed47797a43f31718589b1c..a69bff49ef0863b800c55e18a0d014fc04de1d89 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceHasDxValidator.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceHasDxValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEHASDXVALIDATOR_H_
-#define MANTID_API_WORKSPACEHASDXVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 
@@ -29,4 +28,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_WORKSPACEHASDXVALIDATOR_H_ */
diff --git a/Framework/API/inc/MantidAPI/WorkspaceHistory.h b/Framework/API/inc/MantidAPI/WorkspaceHistory.h
index 285feb58fe91ec54bc1e2252507b6f1b85a94648..c86c8e34c2803b809276cd4aa051606a07c7c629 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceHistory.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceHistory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEHISTORY_H_
-#define MANTID_API_WORKSPACEHISTORY_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -99,4 +98,3 @@ MANTID_API_DLL std::ostream &operator<<(std::ostream &,
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_WORKSPACEHISTORY_H_*/
diff --git a/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbourInfo.h b/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbourInfo.h
index 78f48732827c170ce978e749592796c85a2e0c9e..9c8aaa2c1e46daf520700e6090655ee90bebf9a1 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbourInfo.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbourInfo.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_NEARESTNEIGHBOURINFO_H_
-#define MANTID_API_NEARESTNEIGHBOURINFO_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidGeometry/IDTypes.h"
@@ -48,4 +47,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_WORKSPACENEARESTNEIGHBOURINFO_H_ */
diff --git a/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbours.h b/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbours.h
index 7a9e8980c41c1e98ccbd49719c83b0cd628722b1..5d45c9636669b58831a26785f09e8933445f9e26 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbours.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceNearestNeighbours.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_GEOMETRY_INSTRUMENT_NEARESTNEIGHBOURS
-#define MANTID_GEOMETRY_INSTRUMENT_NEARESTNEIGHBOURS
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidGeometry/IDTypes.h"
@@ -107,5 +106,3 @@ private:
 
 } // namespace API
 } // namespace Mantid
-
-#endif
diff --git a/Framework/API/inc/MantidAPI/WorkspaceOpOverloads.h b/Framework/API/inc/MantidAPI/WorkspaceOpOverloads.h
index 74d8afe4599dee033c83c4750d38eb2d8a62e878..7cd63ae38c6762956f662b15a849f8f58e60a9f7 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceOpOverloads.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceOpOverloads.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKOPOVERLOADS_H_
-#define MANTID_API_WORKOPOVERLOADS_H_
+#pragma once
 
 #include "MantidAPI/DllConfig.h"
 #include "MantidAPI/MatrixWorkspace_fwd.h"
@@ -91,4 +90,3 @@ struct MANTID_API_DLL WorkspaceHelpers {
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_WORKOPOVERLOADS_H_ */
diff --git a/Framework/API/inc/MantidAPI/WorkspaceProperty.h b/Framework/API/inc/MantidAPI/WorkspaceProperty.h
index f0eba3cd9fa20c2438a390850076adbf00a53558..9c720ac85f2219ad1c4629b8237249f88bceda1c 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceProperty.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceProperty.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEPROPERTY_H_
-#define MANTID_API_WORKSPACEPROPERTY_H_
+#pragma once
 
 #include "MantidAPI/IWorkspaceProperty.h"
 #include "MantidKernel/Logger.h"
@@ -152,4 +151,3 @@ Kernel::Logger WorkspaceProperty<TYPE>::g_log("WorkspaceProperty");
 } // namespace API
 } // namespace Mantid
 
-#endif /*MANTID_API_WORKSPACEPROPERTY_H_*/
diff --git a/Framework/API/inc/MantidAPI/WorkspaceUnitValidator.h b/Framework/API/inc/MantidAPI/WorkspaceUnitValidator.h
index 94966027bb7b4a89ae9b44489fe09d0c64e7da75..70562a83408ccada3fb9ca89fe1cb45c3bd5c885 100644
--- a/Framework/API/inc/MantidAPI/WorkspaceUnitValidator.h
+++ b/Framework/API/inc/MantidAPI/WorkspaceUnitValidator.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEUNITVALIDATOR_H_
-#define MANTID_API_WORKSPACEUNITVALIDATOR_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceValidator.h"
 
@@ -35,4 +34,3 @@ private:
 } // namespace API
 } // namespace Mantid
 
-#endif /* MANTID_API_WORKSPACEUNITVALIDATOR_H_ */
\ No newline at end of file
diff --git a/Framework/API/inc/MantidAPI/Workspace_fwd.h b/Framework/API/inc/MantidAPI/Workspace_fwd.h
index 846b023591cdb8897084995f72ad01168dc984f4..d449fc82bdc3227892a806063b7d067ff11c0ecd 100644
--- a/Framework/API/inc/MantidAPI/Workspace_fwd.h
+++ b/Framework/API/inc/MantidAPI/Workspace_fwd.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACE_FWD_H_
-#define MANTID_API_WORKSPACE_FWD_H_
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <memory>
@@ -30,4 +29,3 @@ using Workspace_const_uptr = std::unique_ptr<const Workspace>;
 } // namespace API
 } // namespace Mantid
 
-#endif // MANTID_API_WORKSPACE_FWD_H_
diff --git a/Framework/API/test/ADSValidatorTest.h b/Framework/API/test/ADSValidatorTest.h
index 2300185625af8ae2c4341cd3d9a237593056469a..f18f1ccdc579e615e3d7f9061e8b9c54d6436f74 100644
--- a/Framework/API/test/ADSValidatorTest.h
+++ b/Framework/API/test/ADSValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ADSVALIDATORTEST_H_
-#define MANTID_API_ADSVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -129,4 +128,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_ADSVALIDATORTEST_H_ */
diff --git a/Framework/API/test/AlgorithmFactoryObserverTest.h b/Framework/API/test/AlgorithmFactoryObserverTest.h
index 8bbda51dfd6ab71b4b630eeed6aa89fad1ebf25e..614e23e466b92339cf1aea59cf8d95038a26c8f9 100644
--- a/Framework/API/test/AlgorithmFactoryObserverTest.h
+++ b/Framework/API/test/AlgorithmFactoryObserverTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ALGORITHMFACTORYOBSERVERTEST_H_
-#define ALGORITHMFACTORYOBSERVERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -81,4 +80,3 @@ public:
   }
 };
 
-#endif /* ALGORITHMFACTORYOBSERVERTEST_H_ */
\ No newline at end of file
diff --git a/Framework/API/test/AlgorithmFactoryTest.h b/Framework/API/test/AlgorithmFactoryTest.h
index 0e12c7d16703670cab027b8291e4abb641d7064a..11f6ebee7b88f8b51ac9d76935b463524eaae025 100644
--- a/Framework/API/test/AlgorithmFactoryTest.h
+++ b/Framework/API/test/AlgorithmFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ALGORITHMFACTORYTEST_H_
-#define ALGORITHMFACTORYTEST_H_
+#pragma once
 
 #include "FakeAlgorithms.h"
 #include "MantidAPI/AlgorithmFactory.h"
@@ -244,4 +243,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/AlgorithmHasPropertyTest.h b/Framework/API/test/AlgorithmHasPropertyTest.h
index 266e5bf281aad5704db3971697f59aadb07a92d6..5a1ebbccc19902e5cea26c63811a192bf06d3ec9 100644
--- a/Framework/API/test/AlgorithmHasPropertyTest.h
+++ b/Framework/API/test/AlgorithmHasPropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMHASPROPERTYTEST_H_
-#define MANTID_API_ALGORITHMHASPROPERTYTEST_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/AlgorithmHasProperty.h"
@@ -90,4 +89,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_ALGORITHMHASPROPERTY_H_ */
diff --git a/Framework/API/test/AlgorithmHistoryTest.h b/Framework/API/test/AlgorithmHistoryTest.h
index 69d391a3554615b6f73460a0251b45015fbb2d19..2dffd446ae57182ad0bd9bd71d031725c8cc381f 100644
--- a/Framework/API/test/AlgorithmHistoryTest.h
+++ b/Framework/API/test/AlgorithmHistoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ALGORITHMHISTORYTEST_H_
-#define ALGORITHMHISTORYTEST_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/AlgorithmHistory.h"
@@ -254,4 +253,3 @@ private:
   size_t m_execCount;
 };
 
-#endif /* ALGORITHMHISTORYTEST_H_*/
diff --git a/Framework/API/test/AlgorithmMPITest.h b/Framework/API/test/AlgorithmMPITest.h
index 67c5f5e271e2d8090f299e67020f3affc9b67cec..642ae00cd42b8553ff532caa5cfd9ae9d63c74c3 100644
--- a/Framework/API/test/AlgorithmMPITest.h
+++ b/Framework/API/test/AlgorithmMPITest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ALGORITHMMPITEST_H_
-#define ALGORITHMMPITEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -488,4 +487,3 @@ public:
   }
 };
 
-#endif /*ALGORITHMMPITEST_H_*/
diff --git a/Framework/API/test/AlgorithmManagerTest.h b/Framework/API/test/AlgorithmManagerTest.h
index 3504b2418812bf1fa7a03eb40dbe1225de1f770c..f5ea83e4ad96f939436058e193722a73941ccc29 100644
--- a/Framework/API/test/AlgorithmManagerTest.h
+++ b/Framework/API/test/AlgorithmManagerTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef AlgorithmManagerTest_H_
-#define AlgorithmManagerTest_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -404,4 +403,3 @@ public:
   int m_notificationValue;
 };
 
-#endif /* AlgorithmManagerTest_H_*/
diff --git a/Framework/API/test/AlgorithmPropertyTest.h b/Framework/API/test/AlgorithmPropertyTest.h
index 3cdb1c31c7602aa2ce2c4c46b1c4501f07f0a336..7addc9104c3885de38332f35cb97e0af098bb4e4 100644
--- a/Framework/API/test/AlgorithmPropertyTest.h
+++ b/Framework/API/test/AlgorithmPropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ALGORITHMPROPERTYTEST_H_
-#define MANTID_API_ALGORITHMPROPERTYTEST_H_
+#pragma once
 
 #include "MantidKernel/System.h"
 #include "MantidKernel/Timer.h"
@@ -216,4 +215,3 @@ private:
   }
 };
 
-#endif /* MANTID_API_ALGORITHMPROPERTYTEST_H_ */
diff --git a/Framework/API/test/AlgorithmProxyTest.h b/Framework/API/test/AlgorithmProxyTest.h
index e30baa8ef149a0db537644a2fabb1b9436c78d34..4d01de0fc38a0363f27c8e23188af270d177318b 100644
--- a/Framework/API/test/AlgorithmProxyTest.h
+++ b/Framework/API/test/AlgorithmProxyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ALGORITHMPROXYTEST_H_
-#define ALGORITHMPROXYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -260,4 +259,3 @@ public:
   }
 };
 
-#endif /*ALGORITHMPROXYTEST_H_*/
diff --git a/Framework/API/test/AlgorithmTest.h b/Framework/API/test/AlgorithmTest.h
index e2bf699ff8ec99ffee8698df5b40f091d3808c22..33f4137b1cb9187997daee93de589b6b4e74a6ee 100644
--- a/Framework/API/test/AlgorithmTest.h
+++ b/Framework/API/test/AlgorithmTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ALGORITHMTEST_H_
-#define ALGORITHMTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -1023,4 +1022,3 @@ private:
   MatrixWorkspace_sptr ws3;
 };
 
-#endif /*ALGORITHMTEST_H_*/
diff --git a/Framework/API/test/AnalysisDataServiceObserverTest.h b/Framework/API/test/AnalysisDataServiceObserverTest.h
index c16b3ff1e7577af64fac65fd900e39f248921b77..6d6fbd2a121373e67527e298b71203752ecc1454 100644
--- a/Framework/API/test/AnalysisDataServiceObserverTest.h
+++ b/Framework/API/test/AnalysisDataServiceObserverTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ANALYSISDATASERVICEOBSERVERTEST_H_
-#define ANALYSISDATASERVICEOBSERVERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -240,4 +239,3 @@ public:
   }
 };
 
-#endif /* ANALYSISDATASERVICEOBSERVERTEST_H_ */
\ No newline at end of file
diff --git a/Framework/API/test/AnalysisDataServiceTest.h b/Framework/API/test/AnalysisDataServiceTest.h
index c906d5b1b80e80100edec09abbdc208efebedac6..2ea3bd951d7b5d7b4c2407719fdb3d838186d131 100644
--- a/Framework/API/test/AnalysisDataServiceTest.h
+++ b/Framework/API/test/AnalysisDataServiceTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ANALYSISDATASERVICETEST_H_
-#define ANALYSISDATASERVICETEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -606,4 +605,3 @@ private:
   }
 };
 
-#endif /*ANALYSISDATASERVICETEST_H_*/
diff --git a/Framework/API/test/AsynchronousTest.h b/Framework/API/test/AsynchronousTest.h
index e42e6cb10ad853d76c9b41ebf9e87c48ac3889a4..6d84137b0c07eed470915e88d9ddb91f30ac4141 100644
--- a/Framework/API/test/AsynchronousTest.h
+++ b/Framework/API/test/AsynchronousTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ASYNCHRONOUSTEST_H_
-#define ASYNCHRONOUSTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -295,4 +294,3 @@ std::mutex AsynchronousTest::g_mtx;
 bool AsynchronousTest::g_testStarted = false;
 bool AsynchronousTest::g_execStarted = false;
 
-#endif /*ASYNCHRONOUSTEST_H_*/
diff --git a/Framework/API/test/BinEdgeAxisTest.h b/Framework/API/test/BinEdgeAxisTest.h
index 60b583c0edf8e60606a24ff6ba82d8e8e5cfa54f..e32d4927809840dff88561eec1829c08c379ce30 100644
--- a/Framework/API/test/BinEdgeAxisTest.h
+++ b/Framework/API/test/BinEdgeAxisTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_BINEDGEAXISTEST_H_
-#define MANTID_API_BINEDGEAXISTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -82,4 +81,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_BINEDGEAXISTEST_H_ */
diff --git a/Framework/API/test/BoxControllerTest.h b/Framework/API/test/BoxControllerTest.h
index 6f8245e75bb8223785346b4e075a06233b3d5bcc..77add59d733ebd2a9078226246a754510a011b7a 100644
--- a/Framework/API/test/BoxControllerTest.h
+++ b/Framework/API/test/BoxControllerTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef BOXPLITCONTROLLER_TEST_H
-#define BOXPLITCONTROLLER_TEST_H
+#pragma once
 
 #include "MantidAPI/BoxController.h"
 #include "MantidAPI/IBoxControllerIO.h"
@@ -397,4 +396,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/CitationTest.h b/Framework/API/test/CitationTest.h
index 9b628be1aa8bd108e0350f92d24996d83615e154..7b6db6d61287a1a1bc51666c27593681770f6046 100644
--- a/Framework/API/test/CitationTest.h
+++ b/Framework/API/test/CitationTest.h
@@ -5,8 +5,7 @@
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
 
-#ifndef CITATIONTEST_H_
-#define CITATIONTEST_H_
+#pragma once
 
 #include "MantidAPI/Citation.h"
 #include "MantidTestHelpers/NexusTestHelper.h"
@@ -120,4 +119,3 @@ public:
   }
 };
 
-#endif /* CITATIONTEST_H_ */
\ No newline at end of file
diff --git a/Framework/API/test/CommonBinsValidatorTest.h b/Framework/API/test/CommonBinsValidatorTest.h
index 18222c77fc95d73fc186b6e2a681b3e3fb6df11b..7190a0beb10e6e5ebb34f6a65bdfbebd20653a23 100644
--- a/Framework/API/test/CommonBinsValidatorTest.h
+++ b/Framework/API/test/CommonBinsValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_COMMONBINSVALIDATORTEST_H_
-#define MANTID_API_COMMONBINSVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -63,4 +62,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_COMMONBINSVALIDATORTEST_H_ */
diff --git a/Framework/API/test/CompositeFunctionTest.h b/Framework/API/test/CompositeFunctionTest.h
index d325cb2a67ebc9ed2fb4bdf22618b5417672c450..c6c664f2fc203420fa9c08962b2e5404e738e935 100644
--- a/Framework/API/test/CompositeFunctionTest.h
+++ b/Framework/API/test/CompositeFunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef COMPOSITEFUNCTIONTEST_H_
-#define COMPOSITEFUNCTIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -1247,4 +1246,3 @@ public:
   }
 };
 
-#endif /*COMPOSITEFUNCTIONTEST_H_*/
diff --git a/Framework/API/test/CoordTransformTest.h b/Framework/API/test/CoordTransformTest.h
index f1c481a97918c827408209bfa349379445bff05b..eb355e822334463a2a89f7058a4519270c5daf02 100644
--- a/Framework/API/test/CoordTransformTest.h
+++ b/Framework/API/test/CoordTransformTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_MDEVENTS_COORDTRANSFORMTEST_H_
-#define MANTID_MDEVENTS_COORDTRANSFORMTEST_H_
+#pragma once
 
 #include "MantidAPI/CoordTransform.h"
 #include "MantidKernel/System.h"
@@ -21,4 +20,3 @@ public:
   }
 };
 
-#endif /* MANTID_MDEVENTS_COORDTRANSFORMTEST_H_ */
diff --git a/Framework/API/test/CostFunctionFactoryTest.h b/Framework/API/test/CostFunctionFactoryTest.h
index c49c765715693465b3119456059dabe68a6bd026..dcdfa7a90d192685cfa69b71403166e370ae8642 100644
--- a/Framework/API/test/CostFunctionFactoryTest.h
+++ b/Framework/API/test/CostFunctionFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef COSTFUNCTIONFACTORYTEST_H_
-#define COSTFUNCTIONFACTORYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -58,4 +57,3 @@ public:
   }
 };
 
-#endif /*COSTFUNCTIONFACTORYTEST_H_*/
diff --git a/Framework/API/test/DataProcessorAlgorithmTest.h b/Framework/API/test/DataProcessorAlgorithmTest.h
index 0a49f39dac4e3d0a09c859b8aa0f7a7f29418bc3..db6c958cf21a73d394ede22a9197bc8c24fa199a 100644
--- a/Framework/API/test/DataProcessorAlgorithmTest.h
+++ b/Framework/API/test/DataProcessorAlgorithmTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_DATAPROCESSORALGORITHMTEST_H_
-#define MANTID_API_DATAPROCESSORALGORITHMTEST_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/DataProcessorAlgorithm.h"
@@ -252,4 +251,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_DATAPROCESSORALGORITHMTEST_H_ */
diff --git a/Framework/API/test/DetectorInfoTest.h b/Framework/API/test/DetectorInfoTest.h
index 1c08d29e3efdf8840fe45dabb525d072a7804ed8..abe01d11665b4e5acb393995956bfb0bf167f00c 100644
--- a/Framework/API/test/DetectorInfoTest.h
+++ b/Framework/API/test/DetectorInfoTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_GEOMETRY_DETECTORINFOTEST_H_
-#define MANTID_GEOMETRY_DETECTORINFOTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -563,4 +562,3 @@ private:
   WorkspaceTester m_workspace;
 };
 
-#endif /* MANTID_GEOMETRY_DETECTORINFOTEST_H_ */
diff --git a/Framework/API/test/DetectorSearcherTest.h b/Framework/API/test/DetectorSearcherTest.h
index 7ade5ab4ed3a4f15dfe284335e300221a5bbbe87..5671cfed6fc3238f12f0fac6ecc513380ae8cd8e 100644
--- a/Framework/API/test/DetectorSearcherTest.h
+++ b/Framework/API/test/DetectorSearcherTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_DETECTORSEARCHERTEST_H_
-#define MANTID_API_DETECTORSEARCHERTEST_H_
+#pragma once
 
 #include "MantidAPI/DetectorSearcher.h"
 #include "MantidAPI/ExperimentInfo.h"
@@ -237,4 +236,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/EnabledWhenWorkspaceIsTypeTest.h b/Framework/API/test/EnabledWhenWorkspaceIsTypeTest.h
index 88e061858e380134f38f2aa6af79dbf181a0cf1d..85edade9db10772366a456b53167257e2aca0133 100644
--- a/Framework/API/test/EnabledWhenWorkspaceIsTypeTest.h
+++ b/Framework/API/test/EnabledWhenWorkspaceIsTypeTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ENABLEDWHENWORKSPACEISTYPETEST_H_
-#define MANTID_API_ENABLEDWHENWORKSPACEISTYPETEST_H_
+#pragma once
 
 #include "MantidKernel/System.h"
 #include "MantidKernel/Timer.h"
@@ -91,4 +90,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_ENABLEDWHENWORKSPACEISTYPETEST_H_ */
diff --git a/Framework/API/test/EqualBinSizesValidatorTest.h b/Framework/API/test/EqualBinSizesValidatorTest.h
index 5848c90b6cca3721d4db31af757e2ead9f24c3ad..a03616cfcc06648ac1a1e721321a5d0f978309e5 100644
--- a/Framework/API/test/EqualBinSizesValidatorTest.h
+++ b/Framework/API/test/EqualBinSizesValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_EQUALBINSIZESVALIDATORTEST_H_
-#define MANTID_API_EQUALBINSIZESVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -67,4 +66,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_EQUALBINSIZESVALIDATORTEST_H_ */
diff --git a/Framework/API/test/ExperimentInfoTest.h b/Framework/API/test/ExperimentInfoTest.h
index b85cfc85c29e0b4e4eb0a422746e667b0f6837f1..a53c70b0f4bf3f2622a44bc0782ba47216330a8c 100644
--- a/Framework/API/test/ExperimentInfoTest.h
+++ b/Framework/API/test/ExperimentInfoTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_EXPERIMENTINFOTEST_H_
-#define MANTID_API_EXPERIMENTINFOTEST_H_
+#pragma once
 
 #include "MantidAPI/ExperimentInfo.h"
 #include "MantidAPI/Run.h"
@@ -950,4 +949,3 @@ public:
     m_provisionedInstrument->getBoundingBox(box);
   }
 };
-#endif /* MANTID_API_EXPERIMENTINFOTEST_H_ */
diff --git a/Framework/API/test/ExpressionTest.h b/Framework/API/test/ExpressionTest.h
index 68db7b49d28e29d5a7f5fb29f0e1b13cb05462aa..6b8ea0f70d3e17d3697531b280d432eab6a77c2a 100644
--- a/Framework/API/test/ExpressionTest.h
+++ b/Framework/API/test/ExpressionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef EXPRESSIONTEST_H_
-#define EXPRESSIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -547,4 +546,3 @@ public:
   }
 };
 
-#endif /*EXPRESSIONTEST_H_*/
diff --git a/Framework/API/test/FakeAlgorithms.h b/Framework/API/test/FakeAlgorithms.h
index 0795367a34196d1a8abcf18c3a1b09d0d1de56b1..62eb4e9217edced61c41ed80504deec4af8e0c07 100644
--- a/Framework/API/test/FakeAlgorithms.h
+++ b/Framework/API/test/FakeAlgorithms.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FAKEALGORITHMS_H_
-#define FAKEALGORITHMS_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidKernel/ArrayProperty.h"
@@ -119,4 +118,3 @@ public:
   }
   void exec() override {}
 };
-#endif
diff --git a/Framework/API/test/FileBackedExperimentInfoTest.h b/Framework/API/test/FileBackedExperimentInfoTest.h
index 7765b7aec7f10da9cb2fe844fd95891dc812a403..8dca79f43739fa53ab74b421575e2d4ea24e5714 100644
--- a/Framework/API/test/FileBackedExperimentInfoTest.h
+++ b/Framework/API/test/FileBackedExperimentInfoTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_FILEBACKEDEXPERIMENTINFOTEST_H_
-#define MANTID_API_FILEBACKEDEXPERIMENTINFOTEST_H_
+#pragma once
 
 #include "ExperimentInfoTest.h"
 #include "MantidAPI/FileBackedExperimentInfo.h"
@@ -172,4 +171,3 @@ private:
   std::string m_filename;
 };
 
-#endif /* MANTID_API_FILEBACKEDEXPERIMENTINFOTEST_H_ */
diff --git a/Framework/API/test/FileFinderTest.h b/Framework/API/test/FileFinderTest.h
index b94cf7e80ef682911997f59353c9e416af8702a2..cd4ed2d19c2481575a69097735e7864c0f4fe26a 100644
--- a/Framework/API/test/FileFinderTest.h
+++ b/Framework/API/test/FileFinderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FILEFINDERTEST_H_
-#define FILEFINDERTEST_H_
+#pragma once
 
 #include "MantidAPI/FileFinder.h"
 #include "MantidKernel/ConfigService.h"
@@ -471,7 +470,6 @@ public:
     TS_ASSERT(path.find("CSp78173.Raw") != std::string::npos);
 #else
     TS_ASSERT(path.find("CSP78173.raw") != std::string::npos);
-#endif
     Poco::File file(path);
     TS_ASSERT(file.exists());
     std::string path2 =
@@ -509,7 +507,6 @@ public:
     TS_ASSERT_THROWS_ANYTHING(fileOn2.exists());
     TS_ASSERT_THROWS_ANYTHING(fileOn3.exists());
     TS_ASSERT_THROWS_ANYTHING(fileOn4.exists());
-#endif
 
     fileFinder.setCaseSensitive(startingCaseOption);
   }
@@ -676,4 +673,4 @@ private:
   size_t m_filesToFind;
 };
 
-#endif /*FILEFINDERTEST_H_*/
+ /*FILEFINDERTEST_H_*/
diff --git a/Framework/API/test/FilePropertyTest.h b/Framework/API/test/FilePropertyTest.h
index 15e68d6f96c5e42528026162c6b6d6314c8b5cf7..59fdec87d6cfde584c012aed10487be46083a8b7 100644
--- a/Framework/API/test/FilePropertyTest.h
+++ b/Framework/API/test/FilePropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FILEPROPERTYTEST_H_
-#define FILEPROPERTYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -244,4 +243,3 @@ private:
   }
 };
 
-#endif
diff --git a/Framework/API/test/FrameworkManagerTest.h b/Framework/API/test/FrameworkManagerTest.h
index a76b34f7dc761b75dca684c40ae33a3fb0577e5b..d9e87e3e99104c79fec62b40323828e145814c0b 100644
--- a/Framework/API/test/FrameworkManagerTest.h
+++ b/Framework/API/test/FrameworkManagerTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FRAMEWORKMANAGERTEST_H_
-#define FRAMEWORKMANAGERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -53,7 +52,6 @@ public:
   // Make sure FrameworkManager is always instantiated. This is needed to
   // initialize the MPI environment.
   FrameworkManagerTest() { FrameworkManager::Instance(); }
-#endif
 
   void testConstructor() {
     // Not really much to test
@@ -63,7 +61,6 @@ public:
     // If this is 'MPI Mantid' then test that the mpi environment has been
     // initialized
     TS_ASSERT(boost::mpi::environment::initialized());
-#endif
   }
 
   void testcreateAlgorithm() {
@@ -101,4 +98,4 @@ public:
   }
 };
 
-#endif /*FRAMEWORKMANAGERTEST_H_*/
+ /*FRAMEWORKMANAGERTEST_H_*/
diff --git a/Framework/API/test/FuncMinimizerFactoryTest.h b/Framework/API/test/FuncMinimizerFactoryTest.h
index 583e90cac27161952d760f407d5b4b0ad612a12b..4ae690552247af172e3c9fd53cdea863dfe92126 100644
--- a/Framework/API/test/FuncMinimizerFactoryTest.h
+++ b/Framework/API/test/FuncMinimizerFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCMINIMIZERFACTORYTEST_H_
-#define FUNCMINIMIZERFACTORYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -93,4 +92,3 @@ public:
   }
 };
 
-#endif /*FUNCMINIMIZERFACTORYTEST_H_*/
diff --git a/Framework/API/test/FunctionAttributeTest.h b/Framework/API/test/FunctionAttributeTest.h
index 5b47668af33ba1b6b4750d99ae785c6a2554b9c2..be522ad9ed1cbc707ade14e9a49137e62dbce2c9 100644
--- a/Framework/API/test/FunctionAttributeTest.h
+++ b/Framework/API/test/FunctionAttributeTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTIONATTRIBUTETEST_H_
-#define FUNCTIONATTRIBUTETEST_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/FunctionFactory.h"
@@ -268,4 +267,3 @@ public:
   }
 };
 
-#endif /* FUNCTIONATTRIBUTETEST_H_ */
diff --git a/Framework/API/test/FunctionDomainGeneralTest.h b/Framework/API/test/FunctionDomainGeneralTest.h
index f3178a80e9a4b426393980e03d44bc202af8e708..cedcaa0e53042349a48e2945b88d270f473f4605 100644
--- a/Framework/API/test/FunctionDomainGeneralTest.h
+++ b/Framework/API/test/FunctionDomainGeneralTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTIONDOMAINGENERALTEST_H_
-#define FUNCTIONDOMAINGENERALTEST_H_
+#pragma once
 
 #include "MantidAPI/Column.h"
 #include "MantidAPI/FunctionDomainGeneral.h"
@@ -114,4 +113,3 @@ public:
   }
 };
 
-#endif /*FUNCTIONDOMAINGENERALTEST_H_*/
diff --git a/Framework/API/test/FunctionDomainTest.h b/Framework/API/test/FunctionDomainTest.h
index f1d144942b52d207a5fd863e12ac85714548b4e9..0a7d1b0617415ec8c414d6956843a7b04ea9e51d 100644
--- a/Framework/API/test/FunctionDomainTest.h
+++ b/Framework/API/test/FunctionDomainTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTIONDOMAINTEST_H_
-#define FUNCTIONDOMAINTEST_H_
+#pragma once
 
 #include "MantidAPI/FunctionDomain1D.h"
 #include "MantidAPI/MatrixWorkspace.h"
@@ -83,4 +82,3 @@ private:
   std::vector<double> data;
 };
 
-#endif /*FUNCTIONDOMAINTEST_H_*/
diff --git a/Framework/API/test/FunctionFactoryTest.h b/Framework/API/test/FunctionFactoryTest.h
index 10222ca650f09103a1fd91172850ad817e33b05c..954ffffab9addf0d5071bb82f997dfd134fb117c 100644
--- a/Framework/API/test/FunctionFactoryTest.h
+++ b/Framework/API/test/FunctionFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTIONFACTORYTEST_H_
-#define FUNCTIONFACTORYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -513,4 +512,3 @@ public:
   }
 };
 
-#endif /*FUNCTIONFACTORYTEST_H_*/
diff --git a/Framework/API/test/FunctionParameterDecoratorTest.h b/Framework/API/test/FunctionParameterDecoratorTest.h
index 4c831f6f1b51cba3a06791e249aa725b9b3be8de..6f70f2f9efa5139be342be01d10f1f61f234034d 100644
--- a/Framework/API/test/FunctionParameterDecoratorTest.h
+++ b/Framework/API/test/FunctionParameterDecoratorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WRAPPEDFUNCTIONTEST_H_
-#define MANTID_API_WRAPPEDFUNCTIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -460,4 +459,3 @@ private:
   };
 };
 
-#endif /* MANTID_API_WRAPPEDFUNCTIONTEST_H_ */
diff --git a/Framework/API/test/FunctionPropertyTest.h b/Framework/API/test/FunctionPropertyTest.h
index a3b26260c1fa2cb51fa01fbae230fa9e386e98d1..d7ab77c24c807acbe912ae340a69d6c152d4145f 100644
--- a/Framework/API/test/FunctionPropertyTest.h
+++ b/Framework/API/test/FunctionPropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTIONPROPERTYTEST_H_
-#define FUNCTIONPROPERTYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -127,4 +126,3 @@ private:
   }
 };
 
-#endif /*FUNCTIONPROPERTYTEST_H_*/
diff --git a/Framework/API/test/FunctionTest.h b/Framework/API/test/FunctionTest.h
index 4383397c8a24314c5b7c3484001f27a2ff8e747c..1ebc983ea4d62784f20a9dfab7106452d76293fc 100644
--- a/Framework/API/test/FunctionTest.h
+++ b/Framework/API/test/FunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IFUNCTIONTEST_H_
-#define IFUNCTIONTEST_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/FrameworkManager.h"
@@ -489,4 +488,3 @@ public:
   //}
 };
 
-#endif /*IFUNCTIONTEST_H_*/
diff --git a/Framework/API/test/FunctionValuesTest.h b/Framework/API/test/FunctionValuesTest.h
index efb8f8ec64edb5cbbfdd814ce61394b8e59a83e5..b67258aa49491ad5968a57d1e0eaff234546c84d 100644
--- a/Framework/API/test/FunctionValuesTest.h
+++ b/Framework/API/test/FunctionValuesTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FUNCTIONVALUESTEST_H_
-#define FUNCTIONVALUESTEST_H_
+#pragma once
 
 #include "MantidAPI/FunctionDomain1D.h"
 #include "MantidAPI/FunctionValues.h"
@@ -128,4 +127,3 @@ private:
   std::vector<double> x;
 };
 
-#endif /*FUNCTIONVALUESTEST_H_*/
diff --git a/Framework/API/test/GroupingLoaderTest.h b/Framework/API/test/GroupingLoaderTest.h
index 42da85b5043fc25daed33b484c63498490a7a00d..3d30c8de7642116eda5a58534dafb177b7dc2e24 100644
--- a/Framework/API/test/GroupingLoaderTest.h
+++ b/Framework/API/test/GroupingLoaderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_GROUPINGLOADERTEST_H_
-#define MANTID_API_GROUPINGLOADERTEST_H_
+#pragma once
 
 #include "MantidAPI/FrameworkManager.h"
 #include "MantidAPI/GroupingLoader.h"
@@ -82,4 +81,3 @@ private:
   std::string m_tmpDir;
 };
 
-#endif /* MANTID_API_GROUPINGLOADERTEST_H_ */
diff --git a/Framework/API/test/HistogramValidatorTest.h b/Framework/API/test/HistogramValidatorTest.h
index f41ae19e76d9586d935c415bbb98216ed8771d7c..ff1b39bf9e6bd4e6d3275cca2dc2224eeef3166d 100644
--- a/Framework/API/test/HistogramValidatorTest.h
+++ b/Framework/API/test/HistogramValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_HISTOGRAMVALIDATORTEST_H_
-#define MANTID_API_HISTOGRAMVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -39,4 +38,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_HISTOGRAMVALIDATORTEST_H_ */
diff --git a/Framework/API/test/HistoryItemTest.h b/Framework/API/test/HistoryItemTest.h
index 1d740a141e25f040774b1439fbe8833b769df1ba..0e0c6fad6b5a7f80d8ffa586c9b0dc8f4beebe75 100644
--- a/Framework/API/test/HistoryItemTest.h
+++ b/Framework/API/test/HistoryItemTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef HISTORYITEMTEST_H_
-#define HISTORYITEMTEST_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/HistoryView.h"
@@ -34,4 +33,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/HistoryViewTest.h b/Framework/API/test/HistoryViewTest.h
index d828aab4a0b9ac8699a914b30f5b45be9dd9463f..fbf84c5005aaf1a18d7037c3afac9dcca0928ded 100644
--- a/Framework/API/test/HistoryViewTest.h
+++ b/Framework/API/test/HistoryViewTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef HISTORYVIEWTEST_H_
-#define HISTORYVIEWTEST_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/HistoryView.h"
@@ -357,4 +356,3 @@ public:
   size_t m_execCount;
 };
 
-#endif
diff --git a/Framework/API/test/IEventListTest.h b/Framework/API/test/IEventListTest.h
index d7c59173d0eab46dab6de6cb2ff68dae4d08230d..74a45fba63bd294bd4808e27efb02d62305d1aec 100644
--- a/Framework/API/test/IEventListTest.h
+++ b/Framework/API/test/IEventListTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IEVENTLISTTEST_H_
-#define MANTID_API_IEVENTLISTTEST_H_
+#pragma once
 
 #include "MantidKernel/System.h"
 #include "MantidKernel/Timer.h"
@@ -20,4 +19,3 @@ public:
   void test_Something() {}
 };
 
-#endif /* MANTID_API_IEVENTLISTTEST_H_ */
diff --git a/Framework/API/test/IFunction1DSpectrumTest.h b/Framework/API/test/IFunction1DSpectrumTest.h
index bf71a3cf61ed27b17ca584fb576ff84ddf184dba..f4ff7c42c55a592e5c6689d4915df88f3e5d1e85 100644
--- a/Framework/API/test/IFunction1DSpectrumTest.h
+++ b/Framework/API/test/IFunction1DSpectrumTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTION1DSPECTRUMTEST_H_
-#define MANTID_API_IFUNCTION1DSPECTRUMTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -80,4 +79,3 @@ private:
   };
 };
 
-#endif /* MANTID_API_IFUNCTION1DSPECTRUMTEST_H_ */
diff --git a/Framework/API/test/IFunction1DTest.h b/Framework/API/test/IFunction1DTest.h
index 026978df536717bab6403ea0733fbe245f88160d..e390237b27652c999e9dfc731cbc7b7428f81b6c 100644
--- a/Framework/API/test/IFunction1DTest.h
+++ b/Framework/API/test/IFunction1DTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IFUNCTION1DTEST_H_
-#define IFUNCTION1DTEST_H_
+#pragma once
 
 #include "MantidAPI/FunctionDomain1D.h"
 #include "MantidAPI/FunctionValues.h"
@@ -82,4 +81,3 @@ public:
   }
 };
 
-#endif /*IFUNCTION1DTEST_H_*/
diff --git a/Framework/API/test/IFunctionMDTest.h b/Framework/API/test/IFunctionMDTest.h
index 161e6de4e63b43d6161b3931b9e843a011d4186b..5778c8cb7afc8930e84eced0cb48b7ddab0f49ea 100644
--- a/Framework/API/test/IFunctionMDTest.h
+++ b/Framework/API/test/IFunctionMDTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IFUNCTIONMDTEST_H_
-#define IFUNCTIONMDTEST_H_
+#pragma once
 
 #include "MantidAPI/IFunctionMD.h"
 #include <cxxtest/TestSuite.h>
@@ -35,4 +34,3 @@ public:
   }
 };
 
-#endif /*IFUNCTIONMDTEST_H_*/
diff --git a/Framework/API/test/IFunctionTest.h b/Framework/API/test/IFunctionTest.h
index 3c723b82c8a006c26a7966b27ccd077966ba7e4a..54c35e646c81c5ba8fa6c349d4b274bcdae5f94b 100644
--- a/Framework/API/test/IFunctionTest.h
+++ b/Framework/API/test/IFunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_IFUNCTIONTEST_H_
-#define MANTID_API_IFUNCTIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -146,4 +145,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_IFUNCTIONTEST_H_*/
diff --git a/Framework/API/test/ILatticeFunctionTest.h b/Framework/API/test/ILatticeFunctionTest.h
index e61113188a0c9ba5402fdd51e6e71d025e5707c3..326a50e1bda419059ca4566e336b071865175967 100644
--- a/Framework/API/test/ILatticeFunctionTest.h
+++ b/Framework/API/test/ILatticeFunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ILATTICEFUNCTIONTEST_H_
-#define MANTID_API_ILATTICEFUNCTIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 #include <gmock/gmock.h>
@@ -113,4 +112,3 @@ private:
 
 GNU_DIAG_ON_SUGGEST_OVERRIDE
 
-#endif /* MANTID_API_ILATTICEFUNCTIONTEST_H_ */
diff --git a/Framework/API/test/IMDWorkspaceTest.h b/Framework/API/test/IMDWorkspaceTest.h
index de32c35f3cc6417fc92fc61078fdd51cd1096393..2201079f2814c0f2033291bf3dafe8ff68425545 100644
--- a/Framework/API/test/IMDWorkspaceTest.h
+++ b/Framework/API/test/IMDWorkspaceTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMD_MATRIX_WORKSPACETEST_H_
-#define IMD_MATRIX_WORKSPACETEST_H_
+#pragma once
 
 // Tests the MatrixWorkspace as an IMDWorkspace.
 
@@ -149,4 +148,3 @@ public:
   }
 };
 
-#endif /*IMD_MATRIX_WORKSPACETEST_H_*/
diff --git a/Framework/API/test/ISpectrumTest.h b/Framework/API/test/ISpectrumTest.h
index 241e1b7867c427d4ebe3f79fb0d31b742efa3ecf..67cfad492f697c005160edfd2cf1f43eb5d66bd1 100644
--- a/Framework/API/test/ISpectrumTest.h
+++ b/Framework/API/test/ISpectrumTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_ISPECTRUMTEST_H_
-#define MANTID_API_ISPECTRUMTEST_H_
+#pragma once
 
 #include "MantidKernel/System.h"
 #include "MantidKernel/Timer.h"
@@ -128,4 +127,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_ISPECTRUMTEST_H_ */
diff --git a/Framework/API/test/ImmutableCompositeFunctionTest.h b/Framework/API/test/ImmutableCompositeFunctionTest.h
index 336aaa437dc0c5663188d18f0eb176373328f7ea..816c95cfa8db251694459efc9458ef40720c38b0 100644
--- a/Framework/API/test/ImmutableCompositeFunctionTest.h
+++ b/Framework/API/test/ImmutableCompositeFunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMMUTABLECOMPOSITEFUNCTIONTEST_H_
-#define IMMUTABLECOMPOSITEFUNCTIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -334,4 +333,3 @@ public:
   }
 };
 
-#endif /*IMMUTABLECOMPOSITEFUNCTIONTEST_H_*/
diff --git a/Framework/API/test/ImplicitFunctionFactoryTest.h b/Framework/API/test/ImplicitFunctionFactoryTest.h
index f94b5c4a70e468ed6a25b62b6688c3961f2ba9da..56c31df4e6c75cbf083591afbb7b070e47577db7 100644
--- a/Framework/API/test/ImplicitFunctionFactoryTest.h
+++ b/Framework/API/test/ImplicitFunctionFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMPLICIT_FUNCTION_FACTORY_TEST_H_
-#define IMPLICIT_FUNCTION_FACTORY_TEST_H_
+#pragma once
 
 #include "MantidAPI/ImplicitFunctionFactory.h"
 #include "MantidAPI/ImplicitFunctionParameter.h"
@@ -193,4 +192,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/ImplicitFunctionParameterParserFactoryTest.h b/Framework/API/test/ImplicitFunctionParameterParserFactoryTest.h
index ba81f84ee363a03a9592f9116ad96638401bb27d..66eb4d86a13af4f0e797b4feb6d1cda14c1d314d 100644
--- a/Framework/API/test/ImplicitFunctionParameterParserFactoryTest.h
+++ b/Framework/API/test/ImplicitFunctionParameterParserFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMPLICIT_FUNCTION_PARAMETER_PARSER_FACTORY_TEST_H_
-#define IMPLICIT_FUNCTION_PARAMETER_PARSER_FACTORY_TEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 #include <vector>
@@ -102,4 +101,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/ImplicitFunctionParserFactoryTest.h b/Framework/API/test/ImplicitFunctionParserFactoryTest.h
index e1db7e32ba756d1b3a5a849728f46f8f338ee4d6..46ff50223d06dbdf9e928b64a226658b9df31fcd 100644
--- a/Framework/API/test/ImplicitFunctionParserFactoryTest.h
+++ b/Framework/API/test/ImplicitFunctionParserFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef IMPLICIT_FUNCTION_PARSER_FACTORY_TEST_H_
-#define IMPLICIT_FUNCTION_PARSER_FACTORY_TEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 #include <vector>
@@ -104,4 +103,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/IncreasingAxisValidatorTest.h b/Framework/API/test/IncreasingAxisValidatorTest.h
index 7bfa8b26ec06f51b7b2e8a7058dbefd3c9fa3386..9209aaebc98db7aa260ad8412dc453aab4d65988 100644
--- a/Framework/API/test/IncreasingAxisValidatorTest.h
+++ b/Framework/API/test/IncreasingAxisValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INCREASINGAXISVALIDATORTEST_H_
-#define MANTID_API_INCREASINGAXISVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -62,4 +61,3 @@ private:
   Mantid::API::IncreasingAxisValidator validator;
 };
 
-#endif /* MANTID_API_INCREASINGAXISVALIDATORTEST_H_ */
diff --git a/Framework/API/test/IndexPropertyTest.h b/Framework/API/test/IndexPropertyTest.h
index acffe60e051bf3b37a73f398e63d9ed42f962602..72b6893de2592ea55c25cbedc79b7c4a4b2aadb7 100644
--- a/Framework/API/test/IndexPropertyTest.h
+++ b/Framework/API/test/IndexPropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INDEXPROPERTYTEST_H_
-#define MANTID_API_INDEXPROPERTYTEST_H_
+#pragma once
 
 #include "MantidAPI/IndexProperty.h"
 #include "MantidAPI/IndexTypeProperty.h"
@@ -198,4 +197,3 @@ private:
   IndexTypeProperty m_itypeProp;
 };
 
-#endif /* MANTID_API_INDEXPROPERTYTEST_H_ */
diff --git a/Framework/API/test/IndexTypePropertyTest.h b/Framework/API/test/IndexTypePropertyTest.h
index 1b3d2e9bab298acb1592510356989734b29c4e14..132ec4cf3166d4c5a607c1426946b78297b1d0e0 100644
--- a/Framework/API/test/IndexTypePropertyTest.h
+++ b/Framework/API/test/IndexTypePropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INDEXTYPEPROPERTYTEST_H_
-#define MANTID_API_INDEXTYPEPROPERTYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -94,4 +93,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_INDEXTYPEPROPERTYTEST_H_ */
\ No newline at end of file
diff --git a/Framework/API/test/InstrumentDataServiceTest.h b/Framework/API/test/InstrumentDataServiceTest.h
index 5c9a41fb78edbbf208479cc4237568822bdc740b..ff3ec15bc961a52d51a1249f389d941ed31c4363 100644
--- a/Framework/API/test/InstrumentDataServiceTest.h
+++ b/Framework/API/test/InstrumentDataServiceTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef INSTRUMENTDATASERVICETEST_H_
-#define INSTRUMENTDATASERVICETEST_H_
+#pragma once
 
 #include "MantidAPI/FrameworkManager.h"
 #include "MantidAPI/InstrumentDataService.h"
@@ -121,4 +120,3 @@ private:
   boost::shared_ptr<Instrument> inst1, inst2;
 };
 
-#endif /*INSTRUMENTDATASERVICETEST_H_*/
diff --git a/Framework/API/test/InstrumentValidatorTest.h b/Framework/API/test/InstrumentValidatorTest.h
index 907dc07f7939e579e03bd08fb0ddd60f83a6887d..0da8730939470c5dea23af49920eeecf8ebdf40e 100644
--- a/Framework/API/test/InstrumentValidatorTest.h
+++ b/Framework/API/test/InstrumentValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_INSTRUMENTVALIDATORTEST_H_
-#define MANTID_API_INSTRUMENTVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -53,4 +52,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_INSTRUMENTVALIDATORTEST_H_ */
diff --git a/Framework/API/test/LatticeDomainTest.h b/Framework/API/test/LatticeDomainTest.h
index b1ed9e0d0d496f68e4eb9234988e912a66196adc..2971dd36fbbecc8098021a7458b6333f55c3bb04 100644
--- a/Framework/API/test/LatticeDomainTest.h
+++ b/Framework/API/test/LatticeDomainTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LATTICEDOMAINTEST_H_
-#define MANTID_API_LATTICEDOMAINTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -55,4 +54,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_LATTICEDOMAINTEST_H_ */
diff --git a/Framework/API/test/LiveListenerFactoryTest.h b/Framework/API/test/LiveListenerFactoryTest.h
index 0a8a49e81644c9562812c35f8fefda23ccb4d733..2ecf380b50768e2d5988931642227e08fe1a073a 100644
--- a/Framework/API/test/LiveListenerFactoryTest.h
+++ b/Framework/API/test/LiveListenerFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef LIVELISTENERFACTORYTEST_H_
-#define LIVELISTENERFACTORYTEST_H_
+#pragma once
 
 #include "LiveListenerTest.h"
 #include "MantidAPI/Algorithm.h"
@@ -170,4 +169,3 @@ public:
   }
 };
 
-#endif /* LIVELISTENERFACTORYTEST_H_ */
diff --git a/Framework/API/test/LiveListenerTest.h b/Framework/API/test/LiveListenerTest.h
index 2f70561e7cdb5792ec403e6a0c65e50fb50ab8ff..b47442255d5d5d1dafd82d4d36396841e792b67c 100644
--- a/Framework/API/test/LiveListenerTest.h
+++ b/Framework/API/test/LiveListenerTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef LIVELISTENER_TEST_H_
-#define LIVELISTENER_TEST_H_
+#pragma once
 
 #include "MantidAPI/IAlgorithm.h"
 #include "MantidAPI/LiveListener.h"
@@ -48,4 +47,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/LogFilterGeneratorTest.h b/Framework/API/test/LogFilterGeneratorTest.h
index 0cd05a564802f2c1b289a2588144cdb9931f772b..b7ef6546ab9e59a196983b577e82e470bd4773cf 100644
--- a/Framework/API/test/LogFilterGeneratorTest.h
+++ b/Framework/API/test/LogFilterGeneratorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_LOGFILTERGENERATORTEST_H_
-#define MANTID_API_LOGFILTERGENERATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -190,4 +189,3 @@ private:
   }
 };
 
-#endif /* MANTID_API_LOGFILTERGENERATORTEST_H_ */
diff --git a/Framework/API/test/LogManagerTest.h b/Framework/API/test/LogManagerTest.h
index a6e5733416fa7ed810f8da2a572333b193ff323b..caf94e927e73cb207af078b084961ecfaa1229ae 100644
--- a/Framework/API/test/LogManagerTest.h
+++ b/Framework/API/test/LogManagerTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef LOG_MANAGER_TEST_H_
-#define LOG_MANAGER_TEST_H_
+#pragma once
 
 #include "MantidAPI/LogManager.h"
 #include "MantidGeometry/Instrument/Goniometer.h"
@@ -592,4 +591,3 @@ public:
   std::string m_propName;
 };
 
-#endif
diff --git a/Framework/API/test/MDFrameValidatorTest.h b/Framework/API/test/MDFrameValidatorTest.h
index b1a508b684033d04a101fc556cd4b31d8e309d29..b3eec99eafca5e474f52263b7cecc74d0bff03c4 100644
--- a/Framework/API/test/MDFrameValidatorTest.h
+++ b/Framework/API/test/MDFrameValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_MDUNITVALIDATOR_TEST_H
-#define MANTID_MDUNITVALIDATOR_TEST_H
+#pragma once
 
 #include <boost/make_shared.hpp>
 #include <cxxtest/TestSuite.h>
@@ -79,4 +78,3 @@ public:
   };
 };
 
-#endif // MANTID_MDUNITVALIDATOR_TEST_H
diff --git a/Framework/API/test/MDGeometryTest.h b/Framework/API/test/MDGeometryTest.h
index c8cc963c9b3bbae9a4ac1a7355b122e75b1ef3f3..783867834aaddfc055038ad7128e0bd13496377f 100644
--- a/Framework/API/test/MDGeometryTest.h
+++ b/Framework/API/test/MDGeometryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MDGEOMETRYTEST_H_
-#define MANTID_API_MDGEOMETRYTEST_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/IMDWorkspace.h"
@@ -308,4 +307,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_MDGEOMETRYTEST_H_ */
diff --git a/Framework/API/test/MatrixWorkspaceMDIteratorTest.h b/Framework/API/test/MatrixWorkspaceMDIteratorTest.h
index 8e06b97a699e4348e46724fcaeaee8e8f0dda66f..efbcfb2f8fe24e9dae0a47b79d8b25d6c39a0ffe 100644
--- a/Framework/API/test/MatrixWorkspaceMDIteratorTest.h
+++ b/Framework/API/test/MatrixWorkspaceMDIteratorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MATRIXWORKSPACEMDITERATORTEST_H_
-#define MANTID_API_MATRIXWORKSPACEMDITERATORTEST_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspaceMDIterator.h"
 #include "MantidAPI/SpectrumInfo.h"
@@ -179,4 +178,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_MATRIXWORKSPACEMDITERATORTEST_H_ */
diff --git a/Framework/API/test/MatrixWorkspaceTest.h b/Framework/API/test/MatrixWorkspaceTest.h
index 26918b99e08d761ef4d6c1b006ebe0e34bf7f8bc..528f69c853d0e9b6db267a0e0a5303995d4d5caf 100644
--- a/Framework/API/test/MatrixWorkspaceTest.h
+++ b/Framework/API/test/MatrixWorkspaceTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef WORKSPACETEST_H_
-#define WORKSPACETEST_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/ISpectrum.h"
@@ -2403,4 +2402,3 @@ private:
   boost::shared_ptr<Mantid::Geometry::ParameterMap> m_paramMap;
 };
 
-#endif /*WORKSPACETEST_H_*/
diff --git a/Framework/API/test/MuParserUtilsTest.h b/Framework/API/test/MuParserUtilsTest.h
index 9d25222cb27ce7559e256ef5fb4b2e51749a8499..2ec4d6ce9f756e0f045cf21eefac91399e672220 100644
--- a/Framework/API/test/MuParserUtilsTest.h
+++ b/Framework/API/test/MuParserUtilsTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MUPARSERUTILSTEST_H_
-#define MANTID_API_MUPARSERUTILSTEST_H_
+#pragma once
 
 #include "MantidAPI/MuParserUtils.h"
 #include <cxxtest/TestSuite.h>
@@ -75,4 +74,3 @@ private:
   }
 };
 
-#endif /* MANTID_API_MUPARSERUTILSTEST_H_ */
diff --git a/Framework/API/test/MultiDomainFunctionTest.h b/Framework/API/test/MultiDomainFunctionTest.h
index 239b97ddac605b6f327251798668478dda920a24..de87f5bd59ed649ff7b552a260f32d9d7de3b269 100644
--- a/Framework/API/test/MultiDomainFunctionTest.h
+++ b/Framework/API/test/MultiDomainFunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MULTIDOMAINFUNCTIONTEST_H_
-#define MULTIDOMAINFUNCTIONTEST_H_
+#pragma once
 
 #include "MantidAPI/FunctionDomain1D.h"
 #include "MantidAPI/FunctionFactory.h"
@@ -505,4 +504,3 @@ private:
   JointDomain domain;
 };
 
-#endif /*MULTIDOMAINFUNCTIONTEST_H_*/
diff --git a/Framework/API/test/MultiPeriodGroupAlgorithmTest.h b/Framework/API/test/MultiPeriodGroupAlgorithmTest.h
index 9797626f1df3f88d7feaac184cd1a3c1193b1ef4..3ce5db2744e217c29bf7f853f6628baf2bafa5d2 100644
--- a/Framework/API/test/MultiPeriodGroupAlgorithmTest.h
+++ b/Framework/API/test/MultiPeriodGroupAlgorithmTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MultiPeriodGroupAlgorithmTEST_H_
-#define MANTID_API_MultiPeriodGroupAlgorithmTEST_H_
+#pragma once
 
 #include "MantidAPI/MultiPeriodGroupAlgorithm.h"
 #include "MantidKernel/ArrayProperty.h"
@@ -252,4 +251,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_MultiPeriodGroupAlgorithmTEST_H_ */
diff --git a/Framework/API/test/MultiPeriodGroupTestBase.h b/Framework/API/test/MultiPeriodGroupTestBase.h
index 7a2f320cc13bcb72da1eedea5834a944ee03ec6d..853dc6d6222fb13c2fbfea2cdcc44096be672f88 100644
--- a/Framework/API/test/MultiPeriodGroupTestBase.h
+++ b/Framework/API/test/MultiPeriodGroupTestBase.h
@@ -11,8 +11,7 @@
  *      Author: spu92482
  */
 
-#ifndef MANTID_API_MULTIPERIODGROUPTESTBASE_H_
-#define MANTID_API_MULTIPERIODGROUPTESTBASE_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/MatrixWorkspace.h"
@@ -63,4 +62,3 @@ protected:
   }
 };
 
-#endif /* MANTID_API_MULTIPERIODGROUPTESTBASE_H_ */
diff --git a/Framework/API/test/MultiPeriodGroupWorkerTest.h b/Framework/API/test/MultiPeriodGroupWorkerTest.h
index 4cd57d0cbc516384288ef3deef733961e91d065b..2e1db74361230c245e6e64f4a4ac12ca0f667695 100644
--- a/Framework/API/test/MultiPeriodGroupWorkerTest.h
+++ b/Framework/API/test/MultiPeriodGroupWorkerTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIPERIODGROUPWORKERTEST_H_
-#define MANTID_API_MULTIPERIODGROUPWORKERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -99,4 +98,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_MULTIPERIODGROUPWORKERTEST_H_ */
diff --git a/Framework/API/test/MultipleExperimentInfosTest.h b/Framework/API/test/MultipleExperimentInfosTest.h
index dd2f295385d0c730d61869df6f4a8508630283f6..f13016ed3ab03664504c1c19cd47b953b0d7c271 100644
--- a/Framework/API/test/MultipleExperimentInfosTest.h
+++ b/Framework/API/test/MultipleExperimentInfosTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIPLEEXPERIMENTINFOSTEST_H_
-#define MANTID_API_MULTIPLEEXPERIMENTINFOSTEST_H_
+#pragma once
 
 #include "MantidKernel/System.h"
 #include "MantidKernel/Timer.h"
@@ -74,4 +73,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_MULTIPLEEXPERIMENTINFOSTEST_H_ */
diff --git a/Framework/API/test/MultipleFilePropertyTest.h b/Framework/API/test/MultipleFilePropertyTest.h
index 24da8f9d48c4ffee19318a0b52f86dc3db4f19f8..ae45fa385e59a04480c5cbbe8e24719b0efb4793 100644
--- a/Framework/API/test/MultipleFilePropertyTest.h
+++ b/Framework/API/test/MultipleFilePropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_MULTIPLEFILEPROPERTYTEST_H_
-#define MANTID_API_MULTIPLEFILEPROPERTYTEST_H_
+#pragma once
 
 #include "MantidAPI/FileProperty.h"
 #include "MantidAPI/MultipleFileProperty.h"
@@ -765,4 +764,3 @@ private:
   }
 };
 
-#endif /* MANTID_API_MULTIPLEFILEPROPERTYTEST_H_ */
diff --git a/Framework/API/test/NotebookBuilderTest.h b/Framework/API/test/NotebookBuilderTest.h
index eadac1881d657083f6d4d13892e63732176cff16..940fc9e40167b498ebab87794238179def8321b4 100644
--- a/Framework/API/test/NotebookBuilderTest.h
+++ b/Framework/API/test/NotebookBuilderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NOTEBOOKBUILDERTEST_H_
-#define MANTID_NOTEBOOKBUILDERTEST_H_
+#pragma once
 
 #include <algorithm>
 #include <cxxtest/TestSuite.h>
@@ -352,4 +351,3 @@ public:
   }
 };
 
-#endif // MANTID_NOTEBOOKBUILDERTEST_H_
diff --git a/Framework/API/test/NotebookWriterTest.h b/Framework/API/test/NotebookWriterTest.h
index 745f68f0ae5324ba88272313ac41c852011c6479..186301de78da7d1a7a0255fb9b1ceb633f3ab99b 100644
--- a/Framework/API/test/NotebookWriterTest.h
+++ b/Framework/API/test/NotebookWriterTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NOTEBOOKWRITERTEST_H_
-#define MANTID_NOTEBOOKWRITERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -61,4 +60,3 @@ public:
   }
 };
 
-#endif // MANTID_NOTEBOOKWRITERTEST_H_
diff --git a/Framework/API/test/NumericAxisTest.h b/Framework/API/test/NumericAxisTest.h
index 2fc2a4c9268da38a5edb76a20ff6c34d80740dd5..6b7a47ea0d23ce835c2610034d73e142177a1386 100644
--- a/Framework/API/test/NumericAxisTest.h
+++ b/Framework/API/test/NumericAxisTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef NUMERICAXISTEST_H_
-#define NUMERICAXISTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -225,4 +224,3 @@ private:
   Axis *numericAxis;
 };
 
-#endif /*NUMERICAXISTEST_H_*/
diff --git a/Framework/API/test/NumericAxisValidatorTest.h b/Framework/API/test/NumericAxisValidatorTest.h
index 2c32bce2f919b3df39c932429a04aa3c2b2370f3..ef51c7186d997b58a626354033016de31a4298e1 100644
--- a/Framework/API/test/NumericAxisValidatorTest.h
+++ b/Framework/API/test/NumericAxisValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_NUMERICAXISVALIDATORTEST_H_
-#define MANTID_API_NUMERICAXISVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -51,4 +50,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_NUMERICAXISVALIDATORTEST_H_ */
diff --git a/Framework/API/test/OrientedLatticeValidatorTest.h b/Framework/API/test/OrientedLatticeValidatorTest.h
index 51ee707562551c3103d2a15792afedaccdbaaaa8..6ef9c3a35754bacafd2e29877a7d0b8cc789a670 100644
--- a/Framework/API/test/OrientedLatticeValidatorTest.h
+++ b/Framework/API/test/OrientedLatticeValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_ORIENTEDLATTICEVALIDATOR_TEST_H
-#define MANTID_ORIENTEDLATTICEVALIDATOR_TEST_H
+#pragma once
 
 #include <boost/make_shared.hpp>
 #include <cxxtest/TestSuite.h>
@@ -50,4 +49,3 @@ public:
   };
 };
 
-#endif // MANTID_ORIENTEDLATTICEVALIDATOR_TEST_H
diff --git a/Framework/API/test/ParamFunctionAttributeHolderTest.h b/Framework/API/test/ParamFunctionAttributeHolderTest.h
index db87f0da160f29d46ee01a17e5fd25b3d50f8c29..71e026e2618277edc1f494777182007ef95bca24 100644
--- a/Framework/API/test/ParamFunctionAttributeHolderTest.h
+++ b/Framework/API/test/ParamFunctionAttributeHolderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PARAMFUNCTIONATTRIBUTEHOLDERTEST_H_
-#define PARAMFUNCTIONATTRIBUTEHOLDERTEST_H_
+#pragma once
 
 #include "MantidAPI/ParamFunction.h"
 #include <cxxtest/TestSuite.h>
@@ -90,4 +89,3 @@ public:
   }
 };
 
-#endif /* PARAMFUNCTIONATTRIBUTEHOLDERTEST_H_ */
diff --git a/Framework/API/test/ParameterReferenceTest.h b/Framework/API/test/ParameterReferenceTest.h
index e05e249ab4dd9fce3eb840763efaa7b23c89d252..2bf2307447eb073b2a7df79bc211c438435e318d 100644
--- a/Framework/API/test/ParameterReferenceTest.h
+++ b/Framework/API/test/ParameterReferenceTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PARAMETERREFERENCETEST_H_
-#define PARAMETERREFERENCETEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -128,4 +127,3 @@ public:
   }
 };
 
-#endif /*PARAMETERREFERENCETEST_H_*/
diff --git a/Framework/API/test/ParameterTieTest.h b/Framework/API/test/ParameterTieTest.h
index 6ddfe2e1399e5941b33d72b6d597339e87c0cc96..c655bddd58301f2767133d1d0300566630f1d93d 100644
--- a/Framework/API/test/ParameterTieTest.h
+++ b/Framework/API/test/ParameterTieTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PARAMETERTIETEST_H_
-#define PARAMETERTIETEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -371,4 +370,3 @@ private:
   }
 };
 
-#endif /*PARAMETERTIETEST_H_*/
diff --git a/Framework/API/test/PeakFunctionIntegratorTest.h b/Framework/API/test/PeakFunctionIntegratorTest.h
index c7e9e83c3d187f3e7a8080e3d6534c32e23f6a71..e007ca6dfe0df0a82446a4d8e27b33d7f5096c34 100644
--- a/Framework/API/test/PeakFunctionIntegratorTest.h
+++ b/Framework/API/test/PeakFunctionIntegratorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PEAKFUNCTIONINTEGRATORTEST_H
-#define PEAKFUNCTIONINTEGRATORTEST_H
+#pragma once
 
 #include "MantidAPI/PeakFunctionIntegrator.h"
 #include <cxxtest/TestSuite.h>
@@ -195,4 +194,3 @@ public:
   }
 };
 
-#endif // PEAKFUNCTIONINTEGRATORTEST_H
diff --git a/Framework/API/test/PrecompiledHeader.h b/Framework/API/test/PrecompiledHeader.h
index f9370b7db2071a4451fbff1cc0a1df94d475667d..2b4559aad0760e2961f43676d482a2bdb3b93b8b 100644
--- a/Framework/API/test/PrecompiledHeader.h
+++ b/Framework/API/test/PrecompiledHeader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_APITEST_PRECOMPILED_HEADER_H_
-#define MANTID_APITEST_PRECOMPILED_HEADER_H_
+#pragma once
 
 // cxxtest
 #include <cxxtest/WrappedTestSuite.h>
@@ -15,4 +14,3 @@
 #include <string>
 #include <vector>
 
-#endif // MANTID_API_PRECOMPILED_HEADER_H_
\ No newline at end of file
diff --git a/Framework/API/test/ProgressTest.h b/Framework/API/test/ProgressTest.h
index 155ce82ceb9a3f5c81274aeb5d14e721fb1bddb4..489975749327d29242b088205ac42314e601ca68 100644
--- a/Framework/API/test/ProgressTest.h
+++ b/Framework/API/test/ProgressTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PROGRESSTEST_H_
-#define PROGRESSTEST_H_
+#pragma once
 
 #include "MantidAPI/Progress.h"
 #include <cxxtest/TestSuite.h>
@@ -27,4 +26,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/ProjectionTest.h b/Framework/API/test/ProjectionTest.h
index eb51d660366cc18515de4d9e6b7d57ad8b5aa6d3..68226c924f6c60bbdc75464827854586c40c0afe 100644
--- a/Framework/API/test/ProjectionTest.h
+++ b/Framework/API/test/ProjectionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_PROJECTIONTEST_H_
-#define MANTID_API_PROJECTIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -290,4 +289,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_PROJECTIONTEST_H_ */
diff --git a/Framework/API/test/PropertyManagerHelper.h b/Framework/API/test/PropertyManagerHelper.h
index a717d8208b3961238290e7cca805154599430925..d60ddf0e1e5f1ef09c83106a836f659590d35db9 100644
--- a/Framework/API/test/PropertyManagerHelper.h
+++ b/Framework/API/test/PropertyManagerHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef APITEST_PROPERTYMANAGERHELPER_H_
-#define APITEST_PROPERTYMANAGERHELPER_H_
+#pragma once
 
 #include "MantidKernel/PropertyManager.h"
 
@@ -22,4 +21,3 @@ public:
   using PropertyManager::setProperty;
 };
 
-#endif
diff --git a/Framework/API/test/RawCountValidatorTest.h b/Framework/API/test/RawCountValidatorTest.h
index 9b3c08e1d7c80a32be8f002360080ad616b6eea6..bc538c1e4986bbac437f40f61a7c110149da11a3 100644
--- a/Framework/API/test/RawCountValidatorTest.h
+++ b/Framework/API/test/RawCountValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_RAWCOUNTVALIDATORTEST_H_
-#define MANTID_API_RAWCOUNTVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -41,4 +40,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_RAWCOUNTVALIDATORTEST_H_ */
\ No newline at end of file
diff --git a/Framework/API/test/RemoteJobManagerFactoryTest.h b/Framework/API/test/RemoteJobManagerFactoryTest.h
index a8a339d050b7590ca0d4a012355beabfbd2845e7..34140a9e85eaf10d9e406e352afa75913221ac37 100644
--- a/Framework/API/test/RemoteJobManagerFactoryTest.h
+++ b/Framework/API/test/RemoteJobManagerFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef REMOTEJOBMANAGERFACTORYTEST_H_
-#define REMOTEJOBMANAGERFACTORYTEST_H_
+#pragma once
 
 #include "MantidAPI/RemoteJobManagerFactory.h"
 #include "MantidKernel/ConfigService.h"
@@ -226,4 +225,3 @@ const std::string RemoteJobManagerFactoryTest::SNSFac = "SNS";
 const std::string RemoteJobManagerFactoryTest::ISISFac = "ISIS";
 const std::string RemoteJobManagerFactoryTest::FermiName = "Fermi";
 
-#endif /* REMOTEJOBMANAGERFACTORYTEST_H_ */
diff --git a/Framework/API/test/ResizeRectangularDetectorHelperTest.h b/Framework/API/test/ResizeRectangularDetectorHelperTest.h
index a0dcba5b793224b9bb63572272ace3f036dc33aa..6aba92a783b4d9657d9ebb576c4f0d9972b2ec5e 100644
--- a/Framework/API/test/ResizeRectangularDetectorHelperTest.h
+++ b/Framework/API/test/ResizeRectangularDetectorHelperTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_RESIZERECTANGULARDETECTORHELPERTEST_H_
-#define MANTID_API_RESIZERECTANGULARDETECTORHELPERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -79,4 +78,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_RESIZERECTANGULARDETECTORHELPERTEST_H_ */
diff --git a/Framework/API/test/RunTest.h b/Framework/API/test/RunTest.h
index 8522c39a36d7411d0245875fd0f1cc1afa2d67ec..e6d9544f5d6f7dbe3648996b3a10432ab844d1e7 100644
--- a/Framework/API/test/RunTest.h
+++ b/Framework/API/test/RunTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef RUNTEST_H_
-#define RUNTEST_H_
+#pragma once
 
 #include "MantidAPI/Run.h"
 #include "MantidGeometry/Instrument/Goniometer.h"
@@ -643,4 +642,3 @@ public:
   std::string m_propName;
 };
 
-#endif
diff --git a/Framework/API/test/SampleShapeValidatorTest.h b/Framework/API/test/SampleShapeValidatorTest.h
index eda018dbddb32bc18ec8df1f5c2e0a613304b16b..830b0662815aeae4d94c87ebe960df941d56f59c 100644
--- a/Framework/API/test/SampleShapeValidatorTest.h
+++ b/Framework/API/test/SampleShapeValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SAMPLESHAPEVALIDATORTEST_H_
-#define MANTID_API_SAMPLESHAPEVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -47,4 +46,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_SAMPLESHAPEVALIDATORTEST_H_ */
diff --git a/Framework/API/test/SampleTest.h b/Framework/API/test/SampleTest.h
index 1885279be6369336ae6a00a38915cb1ab6563a82..4dcc4cc5b407fb3e3728a6a4353841d96f38c927 100644
--- a/Framework/API/test/SampleTest.h
+++ b/Framework/API/test/SampleTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TESTSAMPLE_H_
-#define TESTSAMPLE_H_
+#pragma once
 
 #include "MantidAPI/Sample.h"
 #include "MantidGeometry/Crystal/CrystalStructure.h"
@@ -362,4 +361,3 @@ public:
   }
 };
 
-#endif /*TESTSAMPLE_H_*/
diff --git a/Framework/API/test/SampleValidatorTest.h b/Framework/API/test/SampleValidatorTest.h
index 63b273fb0f1d2c38796831e659a3fbe000202ccc..677e8db4024ec0fb86c34442a38514f72f4cc5ec 100644
--- a/Framework/API/test/SampleValidatorTest.h
+++ b/Framework/API/test/SampleValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SAMPLEVALIDATORTEST_H_
-#define MANTID_API_SAMPLEVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -49,4 +48,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_SAMPLEVALIDATORTEST_H_ */
diff --git a/Framework/API/test/ScopedWorkspaceTest.h b/Framework/API/test/ScopedWorkspaceTest.h
index bfd0fe322236ac95a46e5291021c6e8ab4754b2e..d973929dde98bc12c582ba920206d8c52476c51e 100644
--- a/Framework/API/test/ScopedWorkspaceTest.h
+++ b/Framework/API/test/ScopedWorkspaceTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SCOPEDWORKSPACETEST_H_
-#define MANTID_API_SCOPEDWORKSPACETEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -220,4 +219,3 @@ private:
   AnalysisDataServiceImpl &m_ads;
 };
 
-#endif /* MANTID_API_SCOPEDWORKSPACETEST_H_ */
diff --git a/Framework/API/test/ScriptBuilderTest.h b/Framework/API/test/ScriptBuilderTest.h
index 5791a6e12da1935d3efdc083b59f60fbd77bdff6..860052e79b6601261620f904d2c114f6efc66409 100644
--- a/Framework/API/test/ScriptBuilderTest.h
+++ b/Framework/API/test/ScriptBuilderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_SCRIPTBUILDERTEST_H_
-#define MANTID_SCRIPTBUILDERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -591,4 +590,3 @@ private:
   MatrixWorkspace_sptr m_testWS;
 };
 
-#endif // MANTID_SCRIPTBUILDERTEST_H_
diff --git a/Framework/API/test/SingleCountValidatorTest.h b/Framework/API/test/SingleCountValidatorTest.h
index 833a21f2be72d1b5ce620552004cc9e219d1551e..c8d807a94388e9515e091c5eccbc2daa7a9043c0 100644
--- a/Framework/API/test/SingleCountValidatorTest.h
+++ b/Framework/API/test/SingleCountValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SINGLECOUNTVALIDATORTEST_H_
-#define MANTID_API_SINGLECOUNTVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -86,4 +85,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_SINGLECOUNTVALIDATORTEST_H_ */
diff --git a/Framework/API/test/SpectraAxisTest.h b/Framework/API/test/SpectraAxisTest.h
index e8fe835ad36ba24cb96c954a8b194d3ef015cf2b..4cfeb92a497b88aa5c48a7eee8888e0abed1b012 100644
--- a/Framework/API/test/SpectraAxisTest.h
+++ b/Framework/API/test/SpectraAxisTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef SPECTRAAXISTEST_H_
-#define SPECTRAAXISTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -127,4 +126,3 @@ private:
   Axis *spectraAxis;
 };
 
-#endif /*SPECTRAAXISTEST_H_*/
diff --git a/Framework/API/test/SpectraAxisValidatorTest.h b/Framework/API/test/SpectraAxisValidatorTest.h
index 9b23c9bd718688dd9376773d0236b970f5303a89..c91efa34dd518131bb6b6b1141e9015c246a08f9 100644
--- a/Framework/API/test/SpectraAxisValidatorTest.h
+++ b/Framework/API/test/SpectraAxisValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRAAXISVALIDATORTEST_H_
-#define MANTID_API_SPECTRAAXISVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -51,4 +50,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_SPECTRAAXISVALIDATORTEST_H_ */
diff --git a/Framework/API/test/SpectrumDetectorMappingTest.h b/Framework/API/test/SpectrumDetectorMappingTest.h
index 18a918d1605ffb97ce9203bb8503c9d05948c0c2..bcf712d2197e6a284a8fe20537091c2072795d5f 100644
--- a/Framework/API/test/SpectrumDetectorMappingTest.h
+++ b/Framework/API/test/SpectrumDetectorMappingTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRUMDETECTORMAPPINGTEST_H_
-#define MANTID_API_SPECTRUMDETECTORMAPPINGTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -165,4 +164,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_SPECTRUMDETECTORMAPPINGTEST_H_ */
diff --git a/Framework/API/test/SpectrumInfoTest.h b/Framework/API/test/SpectrumInfoTest.h
index 28dc7e43a87068646723212c8701b2cd1b8a4490..0348dd4470b7b77122afa34b0a8611695dc8a2c1 100644
--- a/Framework/API/test/SpectrumInfoTest.h
+++ b/Framework/API/test/SpectrumInfoTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_SPECTRUMINFOTEST_H_
-#define MANTID_API_SPECTRUMINFOTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -659,4 +658,3 @@ private:
   WorkspaceTester m_workspace;
 };
 
-#endif /* MANTID_API_SPECTRUMINFOTEST_H_ */
diff --git a/Framework/API/test/TempFunctionTest.h b/Framework/API/test/TempFunctionTest.h
index 8432d1c096c1e4d341d14e02b7e20d94ccfd7825..e40e088c2758f1bfa9126d917c3167887c90ec10 100644
--- a/Framework/API/test/TempFunctionTest.h
+++ b/Framework/API/test/TempFunctionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TEMPFUNCTIONTEST_H_
-#define TEMPFUNCTIONTEST_H_
+#pragma once
 
 #include "MantidAPI/IFunctionMW.h"
 #include "MantidAPI/ParamFunction.h"
@@ -83,4 +82,3 @@ public:
   }
 };
 
-#endif /*TEMPFUNCTIONTEST_H_*/
diff --git a/Framework/API/test/TextAxisTest.h b/Framework/API/test/TextAxisTest.h
index b32810b03ddff7fe0e0ec393b82ee84b0361a55f..776a06a368b4fc74439c18bdc16b1f523b619d09 100644
--- a/Framework/API/test/TextAxisTest.h
+++ b/Framework/API/test/TextAxisTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TEXTAXISTEST_H_
-#define TEXTAXISTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -137,4 +136,3 @@ public:
   }
 };
 
-#endif /*TEXTAXISTEST_H_*/
diff --git a/Framework/API/test/TransformScaleFactoryTest.h b/Framework/API/test/TransformScaleFactoryTest.h
index af27ddaf8c4f1671fc5e2d51b90e78f82be077b2..c65d736625c2f2645a0e2f727fda432701c6aca9 100644
--- a/Framework/API/test/TransformScaleFactoryTest.h
+++ b/Framework/API/test/TransformScaleFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TRANSFORMSCALEFACTORYTEST_H_
-#define TRANSFORMSCALEFACTORYTEST_H_
+#pragma once
 
 #include "ITransformScale.h"
 #include "MantidAPI/TransformScaleFactory.h"
@@ -39,4 +38,3 @@ private:
   TransformScaleFactoryImpl &factory;
 };
 
-#endif /* TRANSFORMSCALEFACTORYTEST_H_ */
diff --git a/Framework/API/test/VectorParameterParserTest.h b/Framework/API/test/VectorParameterParserTest.h
index 80a94317a092b701ce79dcd1e755e074a5c7ceb8..df07f208dd2b23c4f6b7f2d6bf2d40bd1040c986 100644
--- a/Framework/API/test/VectorParameterParserTest.h
+++ b/Framework/API/test/VectorParameterParserTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef VECTOR_IMPLICIT_FUNCTION_PARAMETER_PARSER_TEST_H_
-#define VECTOR_IMPLICIT_FUNCTION_PARAMETER_PARSER_TEST_H_
+#pragma once
 
 #include "MantidAPI/VectorParameter.h"
 #include "MantidAPI/VectorParameterParser.h"
@@ -179,4 +178,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/VectorParameterTest.h b/Framework/API/test/VectorParameterTest.h
index b237a50e20764ff171d22e84a95ef77cf2e332ca..0dc750e43e16c680236b992768d11e9b67b39771 100644
--- a/Framework/API/test/VectorParameterTest.h
+++ b/Framework/API/test/VectorParameterTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef VECTOR_IMPLICIT_FUNCTION_PARAMETER_TEST_H_
-#define VECTOR_IMPLICIT_FUNCTION_PARAMETER_TEST_H_
+#pragma once
 
 #include "MantidAPI/VectorParameter.h"
 #include <cxxtest/TestSuite.h>
@@ -135,4 +134,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/WorkspaceFactoryTest.h b/Framework/API/test/WorkspaceFactoryTest.h
index e6401e2bd6f8ed2caf46f1a62291a578bc4f3af6..2997e0c6618f0d79237ac4d5c4313c145e192b80 100644
--- a/Framework/API/test/WorkspaceFactoryTest.h
+++ b/Framework/API/test/WorkspaceFactoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef WORKSPACEFACTORYTEST_H_
-#define WORKSPACEFACTORYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 #include <vector>
@@ -152,4 +151,3 @@ public:
   }
 };
 
-#endif /*WORKSPACEFACTORYTEST_H_*/
diff --git a/Framework/API/test/WorkspaceGroupTest.h b/Framework/API/test/WorkspaceGroupTest.h
index e0810b9763ae47f1417da60402aa521042021857..fa764883f98462582bab7f57a06e30bbc268d118 100644
--- a/Framework/API/test/WorkspaceGroupTest.h
+++ b/Framework/API/test/WorkspaceGroupTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEGROUPTEST_H_
-#define MANTID_API_WORKSPACEGROUPTEST_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/Run.h"
@@ -485,4 +484,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_WORKSPACEGROUPTEST_H_ */
diff --git a/Framework/API/test/WorkspaceHasDxValidatorTest.h b/Framework/API/test/WorkspaceHasDxValidatorTest.h
index 7713fa5e0f213165f770af9feb627eed6c5fea3d..b4f45b726ef7aa93d7c5a770bad898f4e083e229 100644
--- a/Framework/API/test/WorkspaceHasDxValidatorTest.h
+++ b/Framework/API/test/WorkspaceHasDxValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEHASDXVALIDATORTEST_H_
-#define MANTID_API_WORKSPACEHASDXVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -42,4 +41,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_WORKSPACEHASDXVALIDATORTEST_H_ */
diff --git a/Framework/API/test/WorkspaceHistoryIOTest.h b/Framework/API/test/WorkspaceHistoryIOTest.h
index e82dfe93d0d43fc8253a64d39a3dc381c1b24ac7..fa0c415b7b1cc15008c20916f5c25e9df05e6bee 100644
--- a/Framework/API/test/WorkspaceHistoryIOTest.h
+++ b/Framework/API/test/WorkspaceHistoryIOTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef WORKSPACEHISTORYIOTEST_H_
-#define WORKSPACEHISTORYIOTEST_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/AlgorithmFactory.h"
@@ -474,4 +473,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/WorkspaceHistoryTest.h b/Framework/API/test/WorkspaceHistoryTest.h
index 1b7c732c7536d92451c4744372244462790add61..9da45b5da1822cde16cca6e00962fa9a710fae98 100644
--- a/Framework/API/test/WorkspaceHistoryTest.h
+++ b/Framework/API/test/WorkspaceHistoryTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef WORKSPACEHISTORYTEST_H_
-#define WORKSPACEHISTORYTEST_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/AlgorithmFactory.h"
@@ -229,4 +228,3 @@ private:
   WorkspaceHistory m_1000000Histories2;
 };
 
-#endif
diff --git a/Framework/API/test/WorkspaceNearestNeighbourInfoTest.h b/Framework/API/test/WorkspaceNearestNeighbourInfoTest.h
index 3f7428717d0faf87b57d1ec1bfeb6c7f7c6d54ca..0ff15d21a2178774aec8d411dcf35e8d21f89c9e 100644
--- a/Framework/API/test/WorkspaceNearestNeighbourInfoTest.h
+++ b/Framework/API/test/WorkspaceNearestNeighbourInfoTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_NEARESTNEIGHBOURINFOTEST_H_
-#define MANTID_API_NEARESTNEIGHBOURINFOTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -66,4 +65,3 @@ private:
   WorkspaceTester workspace;
 };
 
-#endif /* MANTID_API_NEARESTNEIGHBOURINFOTEST_H_ */
diff --git a/Framework/API/test/WorkspaceNearestNeighboursTest.h b/Framework/API/test/WorkspaceNearestNeighboursTest.h
index c8447ad66ef256414bbf44948fd931b2bf2d4352..c60002b2bdf78235ad71d81cfea1f49704f11898 100644
--- a/Framework/API/test/WorkspaceNearestNeighboursTest.h
+++ b/Framework/API/test/WorkspaceNearestNeighboursTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TEST_GEOMETRY_NEARESTNEIGHBOURS
-#define MANTID_TEST_GEOMETRY_NEARESTNEIGHBOURS
+#pragma once
 
 #include "MantidAPI/SpectrumInfo.h"
 #include "MantidAPI/WorkspaceNearestNeighbours.h"
@@ -241,4 +240,3 @@ public:
   }
 };
 
-#endif /* MANTID_TEST_GEOMETRY_NEARESTNEIGHBOURS */
diff --git a/Framework/API/test/WorkspaceOpOverloadsTest.h b/Framework/API/test/WorkspaceOpOverloadsTest.h
index da551009eb8c514d2c82f0d9c7d313c1df831a08..3e46f32b5bcebb1c9048dbf3b706966b0457a161 100644
--- a/Framework/API/test/WorkspaceOpOverloadsTest.h
+++ b/Framework/API/test/WorkspaceOpOverloadsTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef WORKSPACEOPOVERLOADSTEST_H_
-#define WORKSPACEOPOVERLOADSTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -174,4 +173,3 @@ public:
   }
 };
 
-#endif
diff --git a/Framework/API/test/WorkspacePropertyTest.h b/Framework/API/test/WorkspacePropertyTest.h
index 5e53ae3b7c92eabcf15306a41a5f95343bed447b..8b443280abd5296d76c59c84a8b125e935740110 100644
--- a/Framework/API/test/WorkspacePropertyTest.h
+++ b/Framework/API/test/WorkspacePropertyTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef WORKSPACEPROPERTYTEST_H_
-#define WORKSPACEPROPERTYTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -417,4 +416,3 @@ private:
   WorkspacePropertyWorkspace_uptr wsp6;
 };
 
-#endif /*WORKSPACEPROPERTYTEST_H_*/
diff --git a/Framework/API/test/WorkspaceUnitValidatorTest.h b/Framework/API/test/WorkspaceUnitValidatorTest.h
index 3c36bd81f63530768a5f95af3a4a69341558488b..9ec72036c734f38e8c53d6a21dadaa6dc43012a2 100644
--- a/Framework/API/test/WorkspaceUnitValidatorTest.h
+++ b/Framework/API/test/WorkspaceUnitValidatorTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_API_WORKSPACEUNITVALIDATORTEST_H_
-#define MANTID_API_WORKSPACEUNITVALIDATORTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -39,4 +38,3 @@ public:
   }
 };
 
-#endif /* MANTID_API_WORKSPACEUNITVALIDATORTEST_H_ */