Not all Irish floo (& glad your family did't experience it), but a lot of Irish got flack because of the 'troubles' and the IRA, i heard it at work occasionally and heard it from Irish people. edit : one colleague of my schoolmaster dad, the man had lived in England since he was in his twenties! He experienced derogatory remarks from the kids he taught, he could forgive those, but also from neighbours. I worked with a couple of Irish people (still do, different people), notably one man and one woman who with her husband brought up a family here, who experienced the same.
Such prejudice usually came from either the thoughtless young or the less educated sections of society & from what I see, same attitude applies to Muslims.