Irish jokes apart (and some are now being retold as blonde jokes) I have not come across any genuine anti Irish sentiment in England. For myself I have visited Ireland many times and there or here I have yet to meet an Irish person i did not like (perhaps I have been lucky).
Curator referred to one of his "Active Service Units" operating while he was here. These were actually vicious indisciminate killers.
Only in a country of saints would there be no backlash against the country they claimed to be acting for. In the same way that there was some anti Japanese feeling in the USA after Pearl Harbour.

They detonated, without any warning, large bombs of dynamite packed with coach bolts in crowded pubs, killing, maiming and mutilating indiscriminately.
They bombed shopping streets, firebombed shops, planted bombs in postboxes on busy streets, and fired submachine guns into a crowded resaurant.
When cornered by armed police they took a poor terrified middle aged couple hostage in their home for days, but promptly surrendered when they thought the SAS were coming. They were only brave when attacking helpless, undefended and unarmed victims.

Shamefully they were welcomed home as heroes by Gerry Adams.