diff --git a/Code/Mantid/instrument/BASIS_Definition.xml b/Code/Mantid/instrument/BASIS_Definition.xml
index 0ce3275afb8806abd4492b2546bf4e73dabd3fc1..c4dfb665da6e64ea2e1d9d003fe35cafbc97bc0b 100644
--- a/Code/Mantid/instrument/BASIS_Definition.xml
+++ b/Code/Mantid/instrument/BASIS_Definition.xml
@@ -1,5 +1,6 @@
 <?xml version='1.0' encoding='ASCII'?>
-<instrument valid-to="2100-01-31 23:59:59" name="BASIS" valid-from="2012-03-16 11:37:28.380103">
+<instrument valid-to="2100-01-31 23:59:59" name="BASIS" valid-from="2011-08-02 16:09:00">
+  <!-- This geometry used from Run 16693 onward -->
   <!-- Created by Stuart Campbell -->
   <defaults>
     <length unit="metre"/>