Thank you guys for your good replies, although not managing these days I had previously had discussions on the subject and my questions were really to see if my understanding was shared more widely. I agree with your comments.
More detailed explanations can be found here
https://www.caa.co.uk/Commercial-ind...C-declaration/
I think it basically says that if the aircraft is based in the UK and you dispatch from the UK you have to comply with NCC regardless of where your company office is registered.
MM