An arser I know lives in France, his vehicles are UK registered, taxed and MOT'd. He has to bring them back during the year to avoid registering them in france, its just simply easier and legal. .
This time for the 1st few years I did the same but its a pain in the arse from the south of France + with it being an old landie was never quite sure when to book the ferry home.
French wife helped negotiate the twatishry that is the prefecture
I suspect that Les Flics could round up the ilegal UK vehicles if they could be arsed. A pity they dont but I cant see Brexit having much difference.
Periodically the Gendarmes do run random VCPs - not so much since the bacalan - ranging from stopping everyone to specifically targeting UK reg cars
Ive also been pulled a few times owing to the right hooker French plates combo** on general principles I suppose.
I can see if Brexit results in France paying more UK motorists being an easy target for some rebalancing of the books
**and on one occasion not pulled because swmbo was I the pax seat, but from plods expression he would have done had he realised soon enough as it was we were right next to him before he twigged that I was RHD.
Edit at the moment theres much wailing and nashing of teeth ( picked up by the mirror of course) that Brexit means 1000s of ex pats must change their driving licence - this is a Brexit Issue - Mays Fault - confusing for old people - another cost - so unfair - been ok for years etc
Im currently being shunned by the expat community for pointing out that this shouldn't affect any of us because we have all done it all ready** as its a legal requirement already - ergo everyone is complaining that Brexit means we will no longer be able to flout the law.
**My applications in the post because im equally guilty of that one