No you don't.

Wouldn't matter to me if it was a requirement, they'd be replaced the same day with a set displaying the Union Flag (substitute your own choice or nothing) as do mine.

and i don't mean the RMT Union flag despite how effectively their gaffer performs for his members..:-)

The only 'advantage' of an EU plate is you don't need to put a GB sticker on the car if you venture abroad.

Not quite true;of all the EU countries,France has never rescinded the requirement-you might get an awkward policeman one day.

I think the argument in one corner of French officialdom is that the requirement to display a national badge is imposed by treaty and the EU rules cannot override that.

I and many others have driven tens of thousands of miles in France on EU plates and never been challenged. Indeed, on any occasion I've passed police checks I've been waved in the minute they clock the car aas RHD.

The number of cases where 'les flics' pursue the national plate issue is vanishingly small. Of those, most probably relate to drivers who've failed 'le test de attitude' and got le livre thrown at them!!