There is a lot of debate about this. Basically, what it comes down to, as I understand it, is this:
The PPL restricts you to, amongst other things, flight "clear of clouds, in sight of the surface".
The IMC rating removes several restrictions from your license, including, when in Class D or lower airspace, the restrictions on flying "clear of clouds, in sight of the surface". However, the IMC rating is only valid in the UK.
The French authorities will tell you that, when flying France, you can do anything which is legal in France, unless the UK authorities tell you that you can't.
The dubious bit is how the UK authorities interpret the rules about their own rating. The way I read the rules, if you're flying outside the UK, then all of the restrictions which the IMC rating lifts are immediately put back in place. In other words, you're restricted to flight in sight of the surface once again.
However, certain PPRuNers have, I believe, had it in writing from the CAA that the UK-only restriction means that you can not fly IFR outside the UK. Although this is not the way that I read the legislation, if this were the case, then you could legally fly VFR above the clouds (but remember that in certain conditions you have to have at least a minimum vertical separation from the clouds when VFR, whether above or below) outside the UK.
I don't think that answers the question, though - sorry!
FFF
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