Can't be to convinced by this but can anyone else state their opinions.
The CAA clearly states that VFR flight on top of a covered layer is possible for a UK-issued PPL/IMC wherever they may be, France or UK. I understand that flying IFR isn't possible without a valid Instrument Rating, but must the surface always be in sight while flying VFR (but in IMC or above) in France.
Check this article I found. Bottom of Page 9 - Benefits of IMC rating abroad
http://www.caa.co.uk/docs/33/SRG_GAD_GASIL2OF2004.PDF