Hi GWhite, thanks for your suggestion. I'm sure you are correct, but it hasn't changed the results. I still can't explain why I'm seeing systems running Windows 7, Server 2008 R2 and Server 2012. The small sample of machines I checked have different settings which don't show any pattern.
For instance a machine running Win7 which doesn't have this key along with machines running Server 2012 R2 and Server 2016 which do have the key but set to 0, all appear in the results.