There is absolutely social class in Ireland, but it has traditionally been a less stratified class system.
There wasn't really an industrial revolution, apart from in parts of NI, and most of Ireland was overwhelmingly rural and agricultural until comparatively recently, so the big divide was 'strong farmer'/'small farmer'/landless labourer, and various small town business gradations, plus the social status accorded to clergy/religious (becoming a priest was a way of gaining class power, and there were class divides within religious orders, even within individual convents, between choir nuns who brought a dowry and the ones who didn't and were stuck with the domestic work), rather than WC/MC as developed in, say, England, in the 19thc.
And of course the native Irish aristocracy were eradicated or fled the country in the 17thc, so what was left was largely the imported Anglo-Irish, rewarded by Cromwell or the Crown, and owning the majority of Irish land until the Land Acts in the late 19thc and independence.
I would say (having lived in England for years) that it's still less stratified, and that class is less dependent on class shibboleths like specific words than in England, and schools are in general far more socially mixed (there are very few private schools compared to England).
I'm from a very poor WC background, as is DH, but we got out through education and when we came back from living abroad, we were prosperous professionals, now living in an 'old money' part of the city. However, it would take two questions for either of us to be 'placed' in class terms -- where are you from? and where did you go to school? My part of the city is notorious for poverty and petty crime, and my school was likewise notorious for truancy, drinking and a high rate of girls dropping out pregnant (80s). It's now a much more genteel school.
It's a young country, still coming to terms with the boom and bust of the Tiger, comparative prosperity, and being somewhere people want to immigrate to. A lot will probably change in the next ten years again.