I have spoken to the CAA and it also says on there website that if you get a class 1 medical from a full mutual JAA state (theres a list on the CAA webby, but france, germany spain etc are all members) then with a little bit of paper work you can transfer the medical over to the UK with no examination. The UK will then become the state of issue for your license.
I don't see why france will have a problem with it, unless they ask you then I don't think you have to tell them, but you should def look into it
