Reset in America though.
Yes, I know it's a side-effect of it being a big movie, but Dahl is celebrated here. It's tough to hear his voice in a foreign accent, when you grew up hearing it local. (Okay, I'm cheating here - Fantastic Mr Fox was read to us by Sister Kathleen in a Cork accent :))

Sort of. It retained Dahl's sensibilities quite well, I thought. I suspect it felt about as British to me as it felt American to you.