Getting back to the original question. My experience in living in England for a couple of years, and in visiting England often since then, is that yes, plenty of English people are anti-Irish.

These people have a complex of prejudices that interfere with their sight when they're looking at me. When they look at me, they see not me but what they perceive as "an Irish person", and their responses to anything I say or do are mediated through these prejudices.

I haven't experienced the same kind of prejudice among Scots or Welsh; but that's just my own experience. I've certainly seen headlines about Rangers-versus-Celtic battles and the like. (Though these sound more like what you might laughingly call religious differences.)

Reading down through the thread, I've seen some typical examples of prejudiced terms - "The Irish" blew up a postbox; jibes about Cromwell; stereotypes about Irish people bearing grudges, etc.

Perhaps a corrective for anyone with stereotypes about other nationalities would be to read Irene Nemirovsky's book(s) Suite Francaise, which she wrote about the occupation of France, at the time of that occupation.

Nemirovsky was the least prejudiced of people, but she has a sharp eye for its workings.

(It's the best book I've read in the last 10 years, by the way.)