I think the history of England "conquering" the Scots and the Welsh and the role that history plays in the union and governance of the UK today, is at least partially explicable as to why, for example, if you go in a pub in Scotland during the world cup, you'll see plenty of replica shirts of whichever nation Engalnd are playing. That said, I agree with you, for the vast majority of Welsh and Scots, it certainly isn't hatred of English people, far from it. As I say, I've always found people in both nations to be very friendly when I've visited and I genuinely don't think the vast majority cared whether I was English or any other nationality. If you're polite, most people are polite in return.