diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/BinaryOperationMDTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/BinaryOperationMDTestHelper.h
index 707c1aa45e135a573e00ae12423be1ae2fafd408..e9e6fca92cc237d38ea84eae093b0369d1c332c3 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/BinaryOperationMDTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/BinaryOperationMDTestHelper.h
@@ -9,8 +9,7 @@
  *
  *  This header MAY ONLY be included from a test in the MDAlgorithms package.
  *********************************************************************************/
-#ifndef MANTID_MDALGORITHMS_BINARYOPERATIONMDTESTHELPER_H_
-#define MANTID_MDALGORITHMS_BINARYOPERATIONMDTESTHELPER_H_
+#pragma once
 
 #include "MantidDataObjects/MDHistoWorkspace.h"
 
@@ -31,5 +30,3 @@ doTest(std::string algoName, std::string inName, std::string outName,
        std::string otherPropValue = "");
 
 } // namespace UnaryOperationMDTestHelper
-
-#endif
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/BoxControllerDummyIO.h b/Framework/TestHelpers/inc/MantidTestHelpers/BoxControllerDummyIO.h
index 9b1e29d2ccff8c97c7dc1879ec5b80d07cb1956e..4d86568c87a798c0876dc25292a60fa72829580f 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/BoxControllerDummyIO.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/BoxControllerDummyIO.h
@@ -14,8 +14,7 @@
  *  than API (e.g. any algorithm or concrete workspace), even if via the
  *factory.
  *********************************************************************************/
-#ifndef MANTID_TESTHELPERS_BOXCONTROLLER_DUMMUY_IO_H
-#define MANTID_TESTHELPERS_BOXCONTROLLER_DUMMUY_IO_H
+#pragma once
 
 #include "MantidAPI/BoxController.h"
 #include "MantidAPI/IBoxControllerIO.h"
@@ -94,5 +93,4 @@ private:
   /// identified of the file state, if it is open or not.
   bool m_isOpened;
 };
-} // namespace MantidTestHelpers
-#endif
+} // namespace MantidTestHelpers
\ No newline at end of file
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/ComponentCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/ComponentCreationHelper.h
index 95e7393f4cde9abdf1a20718874401038351648e..a8cef19596a348ea15a4a269aad8d825cdc90a63 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/ComponentCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/ComponentCreationHelper.h
@@ -13,8 +13,7 @@
  *a
  *  package higher than Geometry (e.g. API, DataObjects, ...)
  *********************************************************************************/
-#ifndef COMPONENTCREATIONHELPER_H_
-#define COMPONENTCREATIONHELPER_H_
+#pragma once
 
 #include "MantidGeometry/Instrument.h"
 #include "MantidGeometry/Instrument/Detector.h"
@@ -258,5 +257,3 @@ createInstrumentWithPSDTubes(const size_t nTubes = 3,
                              const size_t nPixelsPerTube = 50,
                              const bool mirrorTubes = false);
 } // namespace ComponentCreationHelper
-
-#endif // COMPONENTCREATIONHELPERS_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/DataProcessorTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/DataProcessorTestHelper.h
index d304edc82b59c4394e8bb3eed649ff7a81a7074e..d4cb5026e79f2348b27d4a3a9d8c903ad88ee328 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/DataProcessorTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/DataProcessorTestHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef DATAPROCESSORTESTHELPER_H
-#define DATAPROCESSORTESTHELPER_H
+#pragma once
 
 #include "MantidKernel/System.h"
 
@@ -42,5 +41,3 @@ makeRowData(const std::vector<std::string> &list,
             const std::vector<std::string> &prefixes = {"TOF_", "", "TRANS_"},
             const size_t numSlices = 0);
 } // namespace DataProcessorTestHelper
-
-#endif /*DATAPROCESSORTESTHELPER_H*/
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/FacilityHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/FacilityHelper.h
index 864018ed72d859eb4be1994c25105d884a3ad25d..83aa59d3e3ea4cbd4359d6f86c4b4867fb4fa459 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/FacilityHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/FacilityHelper.h
@@ -10,8 +10,7 @@
  *  This file MAY NOT be modified to use anything from a package other than
  *Kernel.
  *********************************************************************************/
-#ifndef TESTHELPERS_FACILITYHELPER_H_
-#define TESTHELPERS_FACILITYHELPER_H_
+#pragma once
 
 #include "MantidKernel/ConfigService.h"
 #include "MantidKernel/FacilityInfo.h"
@@ -51,5 +50,3 @@ private:
   std::string defFacilityOnStart;
 };
 } // namespace FacilityHelper
-
-#endif /* TESTHELPERS_FACILITYHELPER_H_ */
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/FakeObjects.h b/Framework/TestHelpers/inc/MantidTestHelpers/FakeObjects.h
index 27dd5ea8bd8d4714b82cb81190e35f0e4c377535..a8ef78b5d2341900547cc8f1188041e6f9503fc4 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/FakeObjects.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/FakeObjects.h
@@ -14,8 +14,7 @@
  *  than API (e.g. any algorithm or concrete workspace), even if via the
  *factory.
  *********************************************************************************/
-#ifndef FAKEOBJECTS_H_
-#define FAKEOBJECTS_H_
+#pragma once
 
 /*
  * FakeObjects.h: Fake Tester objects for APITest
@@ -754,5 +753,4 @@ class VariableBinThrowingTester : public AxeslessWorkspaceTester {
 
     return 0;
   }
-};
-#endif /* FAKEOBJECTS_H_ */
+};
\ No newline at end of file
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/FileComparisonHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/FileComparisonHelper.h
index 38b6cd17b8348f45a9625b0b67404847407e99c3..a1292cc407b3d0107b294c8c30cd519bea505f74 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/FileComparisonHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/FileComparisonHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef FILECOMPARISONHELPER_H_
-#define FILECOMPARISONHELPER_H_
+#pragma once
 
 #include <iosfwd>
 #include <iterator>
@@ -48,5 +47,3 @@ bool areFileStreamsEqual(std::ifstream &referenceFileStream,
 bool isEqualToReferenceFile(const std::string &referenceFileName,
                             const std::string &outFileFullPath);
 } // Namespace FileComparisonHelper
-
-#endif // FILECOMPARISONHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/FileResource.h b/Framework/TestHelpers/inc/MantidTestHelpers/FileResource.h
index 0fa8b39909748b9b8211d15847140bf1d2c64f20..bb73e945ccc9b288e90ee1ddf3001afce4eb1708 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/FileResource.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/FileResource.h
@@ -12,8 +12,7 @@
  * @date 06/08/2019
  */
 
-#ifndef MANTID_NEXUSGEOMETRY_FILERESOURCE_H_
-#define MANTID_NEXUSGEOMETRY_FILERESOURCE_H_
+#pragma once
 
 #include <boost/filesystem.hpp>
 #include <iostream>
@@ -35,5 +34,3 @@ protected:
   static void *operator new(std::size_t); // prevent heap allocation of scalar.
   static void *operator new[](std::size_t); // prevent heap allocation of array.
 };
-
-#endif /* MANTID_NEXUSGEOMETRYY_FILERESOURCE_H_ */
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/FunctionCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/FunctionCreationHelper.h
index a209379eca090b49e73dab3e92554e7c1d64f02d..e76ebd8f41ee3cb953578ef57377dda6dc27cbdd 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/FunctionCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/FunctionCreationHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TESTHELPERS_FUNCTIONCREATIONHELPER_H_
-#define MANTID_TESTHELPERS_FUNCTIONCREATIONHELPER_H_
+#pragma once
 
 #include "MantidAPI/IFunction1D.h"
 #include "MantidAPI/ParamFunction.h"
@@ -33,5 +32,3 @@ protected:
 
 } // namespace TestHelpers
 } // namespace Mantid
-
-#endif // MANTID_TESTHELPERS_FUNCTIONCREATIONHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/IndirectFitDataCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/IndirectFitDataCreationHelper.h
index 7f99f92e8c499959cf545e15a572c01a57141a9f..699a255c46d0716dd11e07da160d2947be1c4f99 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/IndirectFitDataCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/IndirectFitDataCreationHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_INDIRECTFITDATACREATIONHELPER_H_
-#define MANTID_INDIRECTFITDATACREATIONHELPER_H_
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/MatrixWorkspace_fwd.h"
@@ -113,5 +112,3 @@ struct AreSpectraEqual : public boost::static_visitor<bool> {
 
 } // namespace IndirectFitDataCreationHelper
 } // namespace Mantid
-
-#endif // MANTID_INDIRECTFITDATACREATIONHELPER_H
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/InstrumentCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/InstrumentCreationHelper.h
index 595f43fd37bd3a0d2796c864249ada396d891939..2979476b1f7b91473c88f8c804c59cc8361d482b 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/InstrumentCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/InstrumentCreationHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef INSTRUMENTCREATIONHELPER_H_
-#define INSTRUMENTCREATIONHELPER_H_
+#pragma once
 
 #include "MantidTestHelpers/ComponentCreationHelper.h"
 
@@ -34,5 +33,3 @@ void addDetector(Mantid::Geometry::Instrument_sptr &instrument,
                  const Mantid::Kernel::V3D &position, const int ID,
                  const std::string &name);
 } // namespace InstrumentCreationHelper
-
-#endif /* INSTRUMENTCREATIONHELPER_H_ */
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/JSONGeometryParserTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/JSONGeometryParserTestHelper.h
index 3a82ba098750e8e03de40ee33125a321266a820e..afecbffe757184dd12b23d00367209ae73a24aa4 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/JSONGeometryParserTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/JSONGeometryParserTestHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TESTHELPERS_JSONGEOMETRYPARSERTESTHELPER_H_
-#define MANTID_TESTHELPERS_JSONGEOMETRYPARSERTESTHELPER_H_
+#pragma once
 
 #ifdef _MSC_VER
 // JSON: non-DLL-interface classkey 'identifier' used as base for
@@ -149,5 +148,3 @@ std::string getFullJSONInstrumentSimpleWithZPixelOffset();
 
 } // namespace TestHelpers
 } // namespace Mantid
-
-#endif // MANTID_TESTHELPERS_JSONGEOMETRYPARSERTESTHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/MDAlgorithmsTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/MDAlgorithmsTestHelper.h
index dbb4917fc4cdfa12d2135f6af38f125288066efa..79f1285ec6497caebd86755712ebf9de57bffaa0 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/MDAlgorithmsTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/MDAlgorithmsTestHelper.h
@@ -9,8 +9,7 @@
  *
  *  This header MAY ONLY be included in the MDalgorithms package
  *********************************************************************************/
-#ifndef MDALGORITHMSTESTHELPER_H
-#define MDALGORITHMSTESTHELPER_H
+#pragma once
 
 #include "MantidDataObjects/MDEventFactory.h"
 
@@ -32,5 +31,3 @@ DataObjects::MDEventWorkspace3Lean::sptr makeFileBackedMDEWwithMDFrame(
 } // namespace MDAlgorithmsTestHelper
 } // namespace MDAlgorithms
 } // namespace Mantid
-
-#endif
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/MDEventsTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/MDEventsTestHelper.h
index 3b5bece96fed2a0a258c3873b6df4480e132b253..178be8a8971e5c2dae94f2c55ddb7ee8340b8dc2 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/MDEventsTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/MDEventsTestHelper.h
@@ -11,8 +11,7 @@
  *of
  *  DataObjects (e.g. Kernel, Geometry, API).
  *********************************************************************************/
-#ifndef MDEVENTSTEST_HELPER_H
-#define MDEVENTSTEST_HELPER_H
+#pragma once
 
 #include "MantidAPI/AnalysisDataService.h"
 #include "MantidAPI/BoxController.h"
@@ -510,5 +509,3 @@ void checkAndDeleteFile(std::string filename);
 } // namespace MDEventsTestHelper
 } // namespace DataObjects
 } // namespace Mantid
-
-#endif
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/MultiDomainFunctionHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/MultiDomainFunctionHelper.h
index 02249d6fb3ec777518ce894c57136c9781916c30..0aae0e60b62d1c043ce3501cd39033186edc0172 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/MultiDomainFunctionHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/MultiDomainFunctionHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TESTHELPERS_MULTIDOMAINFUNCTIONHELPER_H_
-#define MANTID_TESTHELPERS_MULTIDOMAINFUNCTIONHELPER_H_
+#pragma once
 
 #include "MantidAPI/IFunction1D.h"
 #include "MantidAPI/JointDomain.h"
@@ -46,5 +45,3 @@ Mantid::API::MatrixWorkspace_sptr makeMultiDomainWorkspace3();
 
 } // namespace TestHelpers
 } // namespace Mantid
-
-#endif // MANTID_TESTHELPERS_MULTIDOMAINFUNCTIONHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/MuonGroupingXMLHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/MuonGroupingXMLHelper.h
index 882dc1bd7c453ace19708ebce3a17008481cd04e..1409dccf4f379de6158fb08f47f23218d06fdd26 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/MuonGroupingXMLHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/MuonGroupingXMLHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MUONGROUPINGXMLHELPER_H_
-#define MUONGROUPINGXMLHELPER_H_
+#pragma once
 
 #include "MantidAPI/GroupingLoader.h"
 #include "MantidTestHelpers/ScopedFileHelper.h"
@@ -36,5 +35,3 @@ createXMLwithPairsAndGroups(const int &nGroups = 1,
 DLLExport std::string groupingToXML(const Mantid::API::Grouping &grouping);
 
 } // namespace MuonGroupingXMLHelper
-
-#endif /*MUONGROUPINGXMLHELPER_H_*/
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/MuonWorkspaceCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/MuonWorkspaceCreationHelper.h
index d6a6010f4c56ee05a28694baad62e23d1e9162f0..fdbcc6a8e8fa442d016b037dd6d2d163eae8c0ec 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/MuonWorkspaceCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/MuonWorkspaceCreationHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MUONWORKSPACECREATIONHELPER_H_
-#define MUONWORKSPACECREATIONHELPER_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspace.h"
 #include "MantidAPI/WorkspaceGroup.h"
@@ -130,5 +129,3 @@ createWorkspaceGroupConsecutiveDetectorIDs(const int &nWorkspaces, size_t nspec,
                                            const std::string &wsGroupName);
 
 } // namespace MuonWorkspaceCreationHelper
-
-#endif /*MUONWORKSPACECREATIONHELPER_H_*/
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/NexusFileReader.h b/Framework/TestHelpers/inc/MantidTestHelpers/NexusFileReader.h
index 3d7f8d7db904321b2ec65540ca0d89601c579280..8af546dc9073c97a7f3febf37f47f87d509ea1d1 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/NexusFileReader.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/NexusFileReader.h
@@ -5,8 +5,7 @@
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
 
-#ifndef MANTID_NEXUSGEOMETRY_NEXUSFILEREADER_H_
-#define MANTID_NEXUSGEOMETRY_NEXUSFILEREADER_H_
+#pragma once
 
 #include "MantidNexusGeometry/H5ForwardCompatibility.h"
 #include "MantidNexusGeometry/NexusGeometryDefinitions.h"
@@ -416,5 +415,4 @@ private:
 
 }; // NexusFileReader
 } // namespace NexusGeometry
-} // namespace Mantid
-#endif
+} // namespace Mantid
\ No newline at end of file
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/NexusGeometryTestHelpers.h b/Framework/TestHelpers/inc/MantidTestHelpers/NexusGeometryTestHelpers.h
index 415833ddaeabb7e97bc1eb140586d45ea86bf02f..c0e7ee99cd7767acf5b6da7501190d5618eff27c 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/NexusGeometryTestHelpers.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/NexusGeometryTestHelpers.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef NEXUSGEOMETRYTESTHELPERS_H
-#define NEXUSGEOMETRYTESTHELPERS_H
+#pragma once
 
 #include <boost/shared_ptr.hpp>
 #include <vector>
@@ -24,5 +23,3 @@ Pixels generateCoLinearPixels();
 Pixels generateNonCoLinearPixels();
 std::vector<int> getFakeDetIDs();
 } // namespace NexusGeometryTestHelpers
-
-#endif // NEXUSGEOMETRYTESTHELPERS_H
\ No newline at end of file
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/NexusTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/NexusTestHelper.h
index 3b80130a395dda02eb0ec6d4e6cae95fa1d10a9d..32ed327aaf7780f448022badc8a47862be8afbb0 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/NexusTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/NexusTestHelper.h
@@ -10,8 +10,7 @@
  *  This file MAY NOT be modified to use anything from a package other than
  *Kernel.
  *********************************************************************************/
-#ifndef MANTID_NEXUSCPP_NEXUSTESTHELPER_H_
-#define MANTID_NEXUSCPP_NEXUSTESTHELPER_H_
+#pragma once
 
 #include <memory>
 #include <string>
@@ -41,5 +40,3 @@ public:
   /// Do you delete when finished?
   bool deleteFile;
 };
-
-#endif /* MANTID_NEXUSCPP_NEXUSTESTHELPER_H_ */
\ No newline at end of file
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/ONCatHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/ONCatHelper.h
index 53535d578acfabf3dab41d7388e0db8bbc4ab441..31d39e0c82ffb590488cad41525ecc2c3302153d 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/ONCatHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/ONCatHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TESTHELPERS_ONCATHELPER_H_
-#define MANTID_TESTHELPERS_ONCATHELPER_H_
+#pragma once
 
 #include "MantidCatalog/ONCat.h"
 #include "MantidKernel/Exception.h"
@@ -74,5 +73,3 @@ IOAuthTokenStore_uptr make_mock_token_store_already_logged_in();
 
 } // namespace TestHelpers
 } // namespace Mantid
-
-#endif // MANTID_TESTHELPERS_ONCATHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/ParallelAlgorithmCreation.h b/Framework/TestHelpers/inc/MantidTestHelpers/ParallelAlgorithmCreation.h
index c9a15b694811d2ca8ae1c5e0f5da542b1b984c47..fdcee9bc19a1f2db06e13a980ae6a4ab70ac9953 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/ParallelAlgorithmCreation.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/ParallelAlgorithmCreation.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef PARALLELALGORITHMCREATION_H_
-#define PARALLELALGORITHMCREATION_H_
+#pragma once
 
 #include "MantidAPI/IWorkspaceProperty.h"
 #include "MantidKernel/Property.h"
@@ -47,5 +46,3 @@ std::unique_ptr<T> create(const Mantid::Parallel::Communicator &comm) {
 }
 
 } // namespace ParallelTestHelpers
-
-#endif /*PARALLELALGORITHMCREATION_H_*/
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/ParallelRunner.h b/Framework/TestHelpers/inc/MantidTestHelpers/ParallelRunner.h
index 8b3cd8990d7227763f5c03919a5e2a2da49f1765..eb9aae1f373af624960f397298514696081af470 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/ParallelRunner.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/ParallelRunner.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TESTHELPERS_PARALLELRUNNER_H_
-#define MANTID_TESTHELPERS_PARALLELRUNNER_H_
+#pragma once
 
 #include "MantidParallel/Communicator.h"
 #include "MantidParallel/DllConfig.h"
@@ -65,5 +64,3 @@ template <class... Args> void runParallel(Args &&... args) {
 }
 
 } // namespace ParallelTestHelpers
-
-#endif /* MANTID_TESTHELPERS_PARALLELRUNNER_H_ */
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/ReflectometryHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/ReflectometryHelper.h
index 823d41a6bf3fea41f8cdb41d8bfef85fd8c9bf24..d96520315ccf85616eaa1838e74b53c3af75fed5 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/ReflectometryHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/ReflectometryHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TESTHELPERS_REFLECTOMETRYHELPER_H_
-#define MANTID_TESTHELPERS_REFLECTOMETRYHELPER_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspace_fwd.h"
 #include "MantidAPI/WorkspaceGroup_fwd.h"
@@ -64,5 +63,3 @@ MatrixWorkspace_sptr createWorkspaceSingle(const double startX = 1,
                                            const double deltaX = 1);
 } // namespace TestHelpers
 } // namespace Mantid
-
-#endif // MANTID_TESTHELPERS_REFLECTOMETRYHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/SANSInstrumentCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/SANSInstrumentCreationHelper.h
index 91014bd4162cb1ae8107cab844c803d28a170a62..a43a15093f88022ff87d706838d7ca72221ca1e0 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/SANSInstrumentCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/SANSInstrumentCreationHelper.h
@@ -13,8 +13,7 @@
  *  I.e. It can only be used by plugin/algorithm-level packages (e.g.
  *DataHandling)
  *********************************************************************************/
-#ifndef SANSINSTRUMENTCREATIONHELPER_H_
-#define SANSINSTRUMENTCREATIONHELPER_H_
+#pragma once
 
 #include "MantidDataObjects/Workspace2D.h"
 
@@ -52,5 +51,3 @@ public:
   runLoadMappingTable(Mantid::DataObjects::Workspace2D_sptr workspace,
                       int nxbins, int nybins);
 };
-
-#endif // SANSINSTRUMENTCREATIONHELPER_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/ScopedFileHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/ScopedFileHelper.h
index 5e26824cf9c1dec3777b15c2477630e13caf5257..07d6aec3c8f69d0d15f7d581ccf3021f57ae9ed8 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/ScopedFileHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/ScopedFileHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef SCOPEDFILEHELPER_H_
-#define SCOPEDFILEHELPER_H_
+#pragma once
 //------------------------------------------------------------------------------
 // Includes
 //------------------------------------------------------------------------------
@@ -46,5 +45,4 @@ private:
   void *operator new[](size_t);
   void operator delete[](void *);
 };
-} // namespace ScopedFileHelper
-#endif
\ No newline at end of file
+} // namespace ScopedFileHelper
\ No newline at end of file
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/SingleCrystalDiffractionTestHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/SingleCrystalDiffractionTestHelper.h
index 599f5c4c652e178899f6b0498a995116b025158e..1ea977a92de833c08f317e0c1745289f28c00023 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/SingleCrystalDiffractionTestHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/SingleCrystalDiffractionTestHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef SINGLECRYSTALDIFFRACTIONHELPER_H_
-#define SINGLECRYSTALDIFFRACTIONHELPER_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspace.h"
 #include "MantidDataObjects/EventWorkspace.h"
@@ -111,5 +110,3 @@ private:
 };
 } // namespace SingleCrystalDiffractionTestHelper
 } // namespace Mantid
-
-#endif
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/TearDownWorld.h b/Framework/TestHelpers/inc/MantidTestHelpers/TearDownWorld.h
index f7d11460533d49bafb572d885ba44d3ebd3012b8..0ce50096ab621243bb5780cd254721b5c4bafde8 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/TearDownWorld.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/TearDownWorld.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TEARDOWNWORLD_H_
-#define TEARDOWNWORLD_H_
+#pragma once
 
 #include <cxxtest/GlobalFixture.h>
 
@@ -40,5 +39,3 @@ class ClearADS : public CxxTest::GlobalFixture {
 class ClearPropertyManagerDataService : public CxxTest::GlobalFixture {
   bool tearDownWorld() override;
 };
-
-#endif // TEARDOWNWORLD_H_
diff --git a/Framework/TestHelpers/inc/MantidTestHelpers/WorkspaceCreationHelper.h b/Framework/TestHelpers/inc/MantidTestHelpers/WorkspaceCreationHelper.h
index ece2c5c09ec5bfd5c893c0dfd384d3fa28aa40e2..34c40c87105c130e9bca7bd4642f75666ae269b2 100644
--- a/Framework/TestHelpers/inc/MantidTestHelpers/WorkspaceCreationHelper.h
+++ b/Framework/TestHelpers/inc/MantidTestHelpers/WorkspaceCreationHelper.h
@@ -14,8 +14,7 @@
  *  package higher than DataObjects (e.g. any algorithm), even if via the
  *factory.
  *********************************************************************************/
-#ifndef WORKSPACECREATIONHELPER_H_
-#define WORKSPACECREATIONHELPER_H_
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidAPI/AnalysisDataService.h"
@@ -444,5 +443,3 @@ Mantid::API::ITableWorkspace_sptr
 createEPPTableWorkspace(const std::vector<EPPTableRow> &rows);
 
 } // namespace WorkspaceCreationHelper
-
-#endif /*WORKSPACECREATIONHELPER_H_*/
diff --git a/Framework/Types/inc/MantidTypes/Core/DateAndTime.h b/Framework/Types/inc/MantidTypes/Core/DateAndTime.h
index 8fdfa755cd9c6e4c2143c6a26c6474d9d1886ff0..1931747b75a29a65aa8caa037596b88acee2d2f6 100644
--- a/Framework/Types/inc/MantidTypes/Core/DateAndTime.h
+++ b/Framework/Types/inc/MantidTypes/Core/DateAndTime.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TYPES_DATE_AND_TIME_H
-#define MANTID_TYPES_DATE_AND_TIME_H
+#pragma once
 
 #include "MantidTypes/DllConfig.h"
 #ifndef Q_MOC_RUN
@@ -198,5 +197,3 @@ inline int64_t DateAndTime::nanosecondsFromSeconds(double sec) {
 } // namespace Core
 } // namespace Types
 } // namespace Mantid
-
-#endif // MANTID_TYPES_DATE_AND_TIME_H
diff --git a/Framework/Types/inc/MantidTypes/Core/DateAndTimeHelpers.h b/Framework/Types/inc/MantidTypes/Core/DateAndTimeHelpers.h
index f4e882e53893e2b0e57e30a07ddd4fd3c8c07aac..528ff100db649533dcc355ee5b17e2a3a623eb78 100644
--- a/Framework/Types/inc/MantidTypes/Core/DateAndTimeHelpers.h
+++ b/Framework/Types/inc/MantidTypes/Core/DateAndTimeHelpers.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TYPES_CORE_DATEANDTIMEHELPERS_H_
-#define MANTID_TYPES_CORE_DATEANDTIMEHELPERS_H_
+#pragma once
 
 #include "MantidTypes/DllConfig.h"
 
@@ -21,5 +20,3 @@ MANTID_TYPES_DLL bool stringIsPosix(const std::string &date);
 } // namespace Core
 } // namespace Types
 } // namespace Mantid
-
-#endif /* MANTID_TYPES_CORE_DATEANDTIMEHELPERS_H_ */
diff --git a/Framework/Types/inc/MantidTypes/Event/TofEvent.h b/Framework/Types/inc/MantidTypes/Event/TofEvent.h
index 2cc979365f174ebb0cbc947d23612ed043d381c2..db131ba8a9264913f54fb3c8993ca4ea4e0aa6e1 100644
--- a/Framework/Types/inc/MantidTypes/Event/TofEvent.h
+++ b/Framework/Types/inc/MantidTypes/Event/TofEvent.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TYPES_TOFEVENT_H
-#define MANTID_TYPES_TOFEVENT_H
+#pragma once
 
 #include "MantidTypes/Core/DateAndTime.h"
 #include "MantidTypes/DllConfig.h"
@@ -137,5 +136,4 @@ inline double TofEvent::error() const { return 1.0; }
 inline double TofEvent::errorSquared() const { return 1.0; }
 } // namespace Event
 } // namespace Types
-} // namespace Mantid
-#endif // MANTID_TYPES_TOFEVENT_H
+} // namespace Mantid
\ No newline at end of file
diff --git a/Framework/Types/inc/MantidTypes/SpectrumDefinition.h b/Framework/Types/inc/MantidTypes/SpectrumDefinition.h
index bc11339f1e6ebbd1e521cf1d1046cba21d39ac18..7e2a8cb2dbc25b1b93c227bd3f15f7164745ecac 100644
--- a/Framework/Types/inc/MantidTypes/SpectrumDefinition.h
+++ b/Framework/Types/inc/MantidTypes/SpectrumDefinition.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TYPES_SPECTRUMDEFINITION_H_
-#define MANTID_TYPES_SPECTRUMDEFINITION_H_
+#pragma once
 
 #include <algorithm>
 #include <utility>
@@ -69,5 +68,3 @@ public:
 };
 
 } // namespace Mantid
-
-#endif /* MANTID_TYPES_SPECTRUMDEFINITION_H_ */
diff --git a/Framework/Types/test/DateAndTimeHelpersTest.h b/Framework/Types/test/DateAndTimeHelpersTest.h
index d5c38b6002badc0ddb5af753bbcb92bf42bf7460..798f35a91c0947817e35ad27800754d1bf135fc1 100644
--- a/Framework/Types/test/DateAndTimeHelpersTest.h
+++ b/Framework/Types/test/DateAndTimeHelpersTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TYPES_CORE_DATEANDTIMEHELPERSTEST_H_
-#define MANTID_TYPES_CORE_DATEANDTIMEHELPERSTEST_H_
+#pragma once
 
 #include "MantidTypes/Core/DateAndTimeHelpers.h"
 #include <cxxtest/TestSuite.h>
@@ -76,5 +75,3 @@ public:
     TS_ASSERT(!stringIsPosix("1990-Jan-40 03:04:02"))
   }
 };
-
-#endif /* MANTID_TYPES_CORE_DATEANDTIMEHELPERSTEST_H_ */
diff --git a/Framework/Types/test/DateAndTimeTest.h b/Framework/Types/test/DateAndTimeTest.h
index 0714b55f7e85966aaf2f210fe4a7453150ade0ca..b0fe70d005b03af365a415cdf01d585007e1ab10 100644
--- a/Framework/Types/test/DateAndTimeTest.h
+++ b/Framework/Types/test/DateAndTimeTest.h
@@ -11,8 +11,7 @@
  *      Author: janik
  */
 
-#ifndef DATEANDTIMETEST_H_
-#define DATEANDTIMETEST_H_
+#pragma once
 
 #include "MantidTypes/Core/DateAndTime.h"
 #include <ctime>
@@ -471,5 +470,3 @@ public:
     }
   }
 };
-
-#endif /* DATEANDTIMETEST_H_ */
diff --git a/Framework/Types/test/SpectrumDefinitionTest.h b/Framework/Types/test/SpectrumDefinitionTest.h
index 110a4be4ad7bddbddc18ee780381bf0782427e66..1d5da7ddd32df1b9f487bbfb040176b6a3483fe9 100644
--- a/Framework/Types/test/SpectrumDefinitionTest.h
+++ b/Framework/Types/test/SpectrumDefinitionTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_TYPES_SPECTRUMDEFINITIONTEST_H_
-#define MANTID_TYPES_SPECTRUMDEFINITIONTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -107,5 +106,3 @@ public:
     TS_ASSERT_EQUALS(*(def.cbegin()), (std::pair<size_t, size_t>(1, 0)));
   }
 };
-
-#endif /* MANTID_TYPES_SPECTRUMDEFINITIONTEST_H_ */
diff --git a/Framework/Types/test/TofEventTest.h b/Framework/Types/test/TofEventTest.h
index 2e51cc1a9ddfb91b822de687771afd4be9c89ef6..fe7da39ade9f54c6ab21ba3fc51cf96e9c3c4b7b 100644
--- a/Framework/Types/test/TofEventTest.h
+++ b/Framework/Types/test/TofEventTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TOFEVENTTEST_H_
-#define TOFEVENTTEST_H_ 1
+#pragma once
 
 #include "MantidTypes/Event/TofEvent.h"
 #include <cmath>
@@ -51,5 +50,3 @@ public:
     TS_ASSERT_EQUALS(e3.pulseTime(), 321);
   }
 };
-
-#endif