Republic of Ireland not but Northern Ireland is in the UK. United Kingdom of Great Britain and Northern IrelandShould England get to vote on whether Scotland or Ireland remains/remained in the UK?
Most of the subunits of today's European countries were independent states back in ye olden days until some aristocrat(s) or a war forced a merger or acquisition.
In these more democratic times, it seems only just that various subunits might consider voting for self-government and separation from former conquerers.
(As a bit of software, the EU articles are deficient in not handling the case of a member state splitting into two or more states.)
England has always been in favour of Ireland staying in the Union since the 1600s. The Home Rule Bill 1800 was an aye for home rule but they bribed the local landlords and held another vote.