Interesting
Yes he did give his name (surname only you understand - it adds to the gravity of the call) and he gave me a number to call in High Holborn. I believe that he was entirely genuine - maybe a bit outside of his remit but genuine nonetheless.
The aircraft is registered abroad and he got in contact with me by asking the flying club over the phone (data protection, not!).
All very troubling and worrisome. I am disiclined to write in case the can of worms is opened. I can say, however, that it has rather taken the edge off of my appetite for GA and has shown me the worst side of the CAA.
I have dealt a lot with the CAA in my 'proper job' and have found them genuinely good and helpful of late; I thought that a change had occurred until that call.