Hey! Great Western Civilization scholar here... The Normans are an interesting bunch, with even a little stardom, so lets try to be historical. The Vikings became Latin, the Northman, the Nor-Man, from Normandy, I actually got that confirmed by a doctor in history at university! So in Fact, the Norman invasion ended up enforcing French, Latin. The Battle of Hastings famously the Anglo-Saxon King failed to enforce self-rule. Now were some problems, because a French Duke was also the English King, the Hundred Years War. A Thousand years of saying King of France, King of Ireland, and, King of England, as some fantasy power. I was making a few points, northeast names ending in -by like Norby in England mark Viking Cultural significance, but little but Anglo Saxon peoples are marked in DNA markers I think.
I think Celtic Christianity, that's very well researched, the 400s saw Celtic Christianity, marked by monastic and hermit practices. I don't think Christianity was more or less endangered by Anglo Saxons or the Normans, I think the only real pagans in this whole island were Viking invaders the 800's Norwegians, Vikings, the sort that settled inn France did not elsewhere. In fact Anglo Saxons seem to already have been Roman Christian Monk worshippers by this time.
Right , I keep trying to convince people that Bonnie belongs to Scotland! Isn't that right. Look anywhere and everywhere and Scotsman today. Scotsmen aren't hiding from anybody.