You make it sound like the IRA shrugged one day and walked away from terrorism. It was the end result of years of pressure, both political and through law enforcement.
And if you don't think that the Irish weren't treated with scorn and hatred, you don't know English culture. For decades, insulting anti-Irish "humour" was nightly fare on TV. Fun fact: In southeastern England, they burned the Pope in effigy on Guy Fawkes Night until Blair put a stop to it in the 90s. And the Orange Order is still very active, especially in the north.