Because of anomalies in the British Nationality Act at the time of Decolonisation, and the manner in which nationality was defined by many of the newly Independent States (including Northern Ireland and the Republic of Ireland), there are large numbers of people unaware of their rights to British Nationality.
STATUS OF IRELAND & NORTHERN IRELAND
Up until 31.12.1948, Ireland was within the Crown’s Dominions.
Between 01.01.1919 and 17.04.1949, it fell within the Crown’s Dominions, but not for UK Nationality purposes.
From 18.04.1949 until the present day, it was an independent Republic outside of the Commonwealth, but not considered foreign.
Ireland joined the European Union (EU) in 1973.