dstevens,
Many thanks for the informed reply.
Sorry, the 'grey' comment was ambiguous, it only meant it appeared 'grey' to me relating my own lack of knowledge regarding EASA permits and I was struggling to clarify exactly what that meant in terms of maintenance requirements. I didn't intend to imply there was anything shady going or the aircraft on the UK register were in anyway illegal!
Now you have answered all is becoming clear so I now know what I need to be reading up on
