What is the current situation about flying in France on an NPPL or PPL with a medical declaration instead of a Class 2 medical certificate?

I've read the recent CAA guidance - but remain confused !

I posted the same question on the Flyer forums and received this useful reply from Irv Lee:

It took a lot of effort to get a working scheme with the French for the NPPL with SSEA rating to be allowed to visit, and that involved having an ICAO medical. I know this isn't YOUR case, but you might be ...

Why don't we just save ourselves a few billion and call it Schiphol ?

In August the CAA relaxed the medical rules, allowing us to fly in VMC with a "medical declaration" from a GP rather than a full Class 2 medical certificate. (CAA document no. ORS4 -865 spells out the terms and conditions.)

One of the limitations is that the pilot cannot fly outside the UK ...