I have heard this from older Irish people. A lot of flights from Dublin divert through London, and they complain that the British security services should not profile Muslim passengers. They know how it feels they say because back in the 1980’s it was always Irish passengers who were singled out.
But that seems like common sense to me considering that in the 1980s, every terrorist attack in Britain was carried out by the IRA. I don’t think racism had much to do with it. Making sure people didn't get blown up was the priority, and I know that many Irish people appreciated that too. They didn’t want to get blown up either.