My father has always had something of a chip on his shoulder about his own background, as his grandparents' generation was quite well off (pharmacists, lawyers etc), but his parents were poor and bitter. His childhood was marked by poverty and hunger.
My grandmother was very much of the sneering "who do you think you are? do you think you're BETTER than us?" mentality about virtually anything that didn't involve being poor and living in a very poor part of Dublin. My dad bought her a new winter coat once, but she wore the same disgusting dirty old coat to the supermarket every day because she LIKED that people would say "Oh, poor auld Mrs icanteven, sure wouldn't you think that one of her sons would buy her a coat?"
My father was the only one in his family to go to university, and become "middle class". Growing up, we had a country cottage, two cars, riding and violin lessons etc. and although there was NEVER any extra money for fripperies, we never wen't without. My parents were naturally parsimonious, which helped! So my Dad is "working class made good" and he devoted himself to making sure sure that I started life with the privilege and emotional support and love that he didn't have.
But he still thinks of people from the posher parts of Dublin as being "other". As being stuck-up, not like him. Yet oddly, he tolerates and is blind to anti-Irish sentiment here in the UK, where he now lives. It's all very strange.
HOWEVER (maybe outing myself here), he (reluctantly) joined a private members club in Ireland, anxious that it would be terribly posh, and quite ready to hate it and never go, and imagine his surprise when he discovered that all the "posh" old men came from backgrounds JUST like his.
I think in that way, Ireland has the true social mobility that England lacks. You can be born into grinding poverty, but if you make good, nobody judges you for where you came from, only how you behave now.