I blame it all on one guy. What if that plonker who broke ranks on the English side during the battle of Hastings after the English had successfully held the high ground against the French all day stayed in bed that morning, and William the Conqueror just had to bugger off back where he came from? The British Isles turn away from Europe and develop stronger ties with Scandinavian countries over the ensuing centuries. A kingdom of the north eventually extends to encompass Iceland, Greenland, Newfoundland, and the Iroquois confederation well before Columbus. With first contact happening at a time when neither side has any technological advantage, the relationship becomes more of an alliance than a colonization. I don't know how to extrapolate further except to imagine that the world looks very different.