Let's rephrase that a little bit: it's seen as OK by some to give the English a hard time, because it's believed, rightly or wrongly, that the English have given other people a bad time in the past.

The flaws in that attitude are obvious. First, the ones they are taking it out on aren't the ones who gave them trouble. Secondly, they aren't the ones who got the aggro, they only know of it by repute. Thirdly, petty revenge is stupid. And fourth, when you really look into it, it was seldom as simple as "the English hate the xxx" (substitute name of putative victim).

People always want someone to blame for their woes, and Ireland is certainly less developed than many European countries as a direct result of imperial policy. But it's a long way from Lord John Russell to Dick Miles.