FFF
Perhaps a better way to look at this, already mentioned here I believe, is that a basic ICAO PPL doesn't restrict you to be in sight of the surface. The CAA chooses to add this restriction to the UK PPL (among other things, e.g. increasing "VFR" from 1500m to 3000m).
When you get the IMCR, this requirement to be in sight of the surface is removed. While the IMCR itself is valid UK only (the ANO says as much) the aforementioned removal is not thus restricted.
The French DGAC has not restricted its version of the ICAO PPL to be in sight of the surface.
I have this much in writing from the CAA. The pretty clear email has since been distributed to various people and nobody has seen any problems with it (e.g. a CAA official writing in ignorance). If you'd like a copy, PM me.
I would like to know whether the Spanish authorities also allow VMC on top. It's a handy option.
Obviously it's not useful to somebody with the most basic PPL training, or flying a poorly equipped plane, because one has to navigate fully IFR while up there, and (this bit won't be legal...) one may have to climb/descend through the stuff at some point. Presumably this is why French clubs often bar members/renters from doing it. I must admit it is slightly odd, given that the person with the privilege hasn't had the training to navigate on top. But one could make the same point regarding PPL flight in 3km vis, which is legal everywhere but is basically IMC anyway.