LH,
This is what I received from the DGAC this afternoon.
Bonjour,
If your Single Engine Piston class rating has expired you have to pass a
skill test with an examiner on this class. You can pass it I think with a
french examiner who has a JAR licence.
If this class rating is already written on your licence I think that the
French examiner can write the new validity of the rating. but if it is not
the case you will have to send to the UK CAA the copy of the test to have a
new licence.
Perhaps you should ask to the UK CAA to have a confirmation of what I said.
So it looks like it may be possible.
However the schools I have been in contact with are not willing to sign off on my licence. All very frustrating and confusing.
I am based near Dinard so if you have any suggestions it would be most helpfull. I will contact the UK CAA tomorrow and see what they say. More bureaucracy