In my personal canon, England conquered France.
Picard's mother had a French accent, because she was from Corsica.
England never bothered to conquer that.
Lol, I love that idea. That's got to be it.

I just used to think of him as British unless France was specifically mentioned, then I just liked to assume it was a writing error
Your way's much better.
But I did forget about Scotty!
In my defence, I was thinking "English" not "British" (although I did say "British" but that's because I've been conditioned to say "British" when I think "English"!)