Britain is the land mass that includes England, Wales, and Scotland.
William the Conquerer was the first Norman king of England and never had power over Wales and he was mostly successful in gaining homage from King Malcolm III, but never king over the lands.
Edward I about two hundred years later almost pulls it off, but doesn’t quite get a firm grip on Scotland. James I in the early 17th century holds the crown for each of the lands. In 1707 they formalize the relationship with a treaty.
So… No the French did not found Britain.
I think this type of thinking is dealing with Trump the wrong way. Censoring him is pointless. He’s going to say what he wants until it isn’t useful and then pivot. He’s going to do what he wants regardless of what he says.
Don’t take him literally. Take him seriously. Defend at the points of real vulnerability. Counter at the right times. Sow discord and distrust in his hapless helpers and incompetent ranks.
Play to win.