Carte Grise in name of Expat who has gone back to England... any tips?

I’ve one friend who got over this problem Mark. He brought the car to the UK (or Ireland, I can’t remember which) registered it there and then brought it back and registered here. All that was required was the CG and a receipt, continuity on the CG wasn’t a problem. My pal and I have considered doing the same (it was actually his brother who found the innovative method above) but the trip would be quite challenging in the Ami. The car train from Nice has ended and I’ve no idea and it’d cost around €750 to have her delivered to a ferry port.

What’s the barn find method? Maybe I could find the car in his “barn”.