Biggest issue for DS was his perception of being held back a year as the numbers were the same! No amount of explaining could get through to him.
Yes, we've had this conversation about twenty times already! I keep hissing 'But there are two years of Foundation in Ireland!' 
@BrexitIsAShitShow, I am so with you on your username. No, he's definitely not exempt from Irish. Which I'm pleased about as I genuinely want him to learn it -- if we'd come home when he was younger, I'd have considered a Gaelscoil, but I think it would be a bit much to start school mid-year in a new country in a new language.
I have rusty school Irish, but will be able to help him. His father, alas, despite doing Leaving Cert in the same distant year as me (if I say we are among the Peig generations, that will give you an idea), is more of an 'An bhfuil cead agam dul amach?' level.
@Whatstodo2019, that's interesting. I've always picked up other languages easily, and never found Irish difficult, although I was incredibly badly taught -- but for some reason I find the idea of starting to teach DS it much more intimidating than French, which he's just started this year. Possibly because I have no memory of being taught the basics...?
@turkeyboots -- do they really not start learning Irish until first class now? I had no idea! Is that in all primaries?
(And tell me, anyone in general -- are many or most primaries now co-ed? The school DS is going to is, because again it's what he's used to here, and one of his best friends is a girl, but I wondered whether that was at all unusual now, as my old primary has merged with a neighbouring boys' school...)