Yep it is an EFI system.

I could not get any action from Avast/Grime fighter, so I went into add/remove/change Avast and removed the Grimefighter module, so I could install it again. Avast did an update just after that.

The end result is that I can now no longer find any way to see, use or install Grime fighter, so I presume Avast has decided it is not compatible with my system ?

So did I purchase a licence that I cannot use on this machine ?