United Kingdom - Passport & Nationality - Ireland and Northern Ireland - Irish passport
Northern Ireland is an anomaly in Irish and British nationality law. Both countries recognise the territory as falling within their own jurisdiction and sovereignty for the purposes of granting nationality. So where you have a grandparent born in "Ireland", it is important that you are clear as to which part of Ireland they were born in, as a claim to British nationality can arise from a grandparent's birth in Northern Ireland.
- Northern Ireland is recognised by both both Ireland and the UK for nationality purposes; AND
- The Republic of Ireland (the southern part of the island) is not recognised by the UK for British nationality purposes (but only in exceptional/rare circumstances).
A grandparent's birth in Northern Ireland or the Republic of Ireland will result in a claim to Irish nationality (as long as both generations were born in wedlock). This will allow the Irish citizen to live and work in the UK, and to have their partner and dependent children accompany them.