some do some dont.
Dual nationality operates here.
Many opt for Irish for ease of passports etc
That may be true but I gave a Euro to Cabbie in Belfast and was screamed at for 20 minutes about the Queen's money.
I also saw an old female tourist at the giants causeway, have a purchase refused over the euro.
Also I left still wondering what to call Derry/Londonderry.
Everywhere I went I was corrected, politely corrected but corrected.
I guess if you live there you know who supports the crown.
Idiot tourists like myself couldn't.
By the way Northern Ireland is one of the nicest places I have been to and would easily go back again.