Irish Free State
The Free State Constitution declared that every person domiciled in the Irish Free State upon the coming into operation of the (1922) Constitution who was born in Ireland or either of whose parents was born in Ireland or had been ordinarily resident for not less than seven years became a citizen of the Irish Free State within the limits of the jurisdiction of the Irish Free State.
When the Irish Free State ceased to be part of the United Kingdom in 1922, Irish nationals continue to be a British subject and later citizen under UK law. This was largely on the basis that the Free State was a dominion within the British Commonwealth. The United Kingdom view is that Free State citizenship only applied internally. Accordingly, persons born before 1922 remained British subjects unless they had positively deprived themselves of that status.
The Nationality and Citizenship Act 1935 (Irish Free State) repealed the 1914 British Nationality and Status of Aliens Act as amended. Irish citizens born in the territory of the whole of Ireland or those who sought to activate a right to the status derived from either parent whether or not the resident who had been born in Ireland were Irish citizens. This followed from changes in the status of dominions following the Statute of Westminster and the 1930 Commonwealth Conference.
The Aliens Act 1935 was introduced shortly afterwards which defined persons who are not citizens of Saorstát Eireann as aliens. This status did not apply to British citizens, subjects, and peoples of the Commonwealth.
British Nationality Act 1948
The Commonwealth Heads of Government agreed in 1947 that every State except Ireland, which did not participate in the Commonwealth Heads of Government Meeting, would enact its own citizenship law while retaining the common status of British subject.
The British Nationality Act created the status of a citizen of the United Kingdom and Colonies. Ireland left the Commonwealth on 18 April 1949 under the Republic of Ireland Act 1949. A provision was made for retention by certain Irish citizens of status as British subjects without being citizens of a Commonwealth Member State.
Citizens of the Republic of Ireland lost automatic British subject status on 1 January 1949 if they did not acquire citizenship of the UK and Colonies or that of another Commonwealth country. The Act however allowed Irish citizens who were British subjects before 1949 to apply to be Secretary of State to remain a British subject.
The application could be based on previous Crown service, possession of a British passport or associations by way of descent, residence or otherwise with the United Kingdom or any Crown colony, protectorate, British mandated territory or British trust territory.
The status of British subject unlike that of citizenship of the UK and Colonies does not transmit by descent. The 1948 Act, defined the United Kingdom as the United Kingdom of Great Britain and Northern Ireland excluding the Irish Free State. Accordingly, persons born before 6th December 1922 in 26 IFS counties did not become citizens of the UK and the Colonies.
Persons born before 1949 became Citizens of the United Kingdom by descent on 1 January 1949 if they had a father born in the United Kingdom or in a place that was a colony at that date provided the father was married to the person’s mother.
Irish citizens resident in the UK, whether or not British subjects, could apply for citizenship by registration after one year ( which was later increased to five years)
The Ireland Act 1949 (UK) recognised the Republic of Ireland Act 1948 passed by the Oireachtas. The Ireland Act conferred citizenship of the United Kingdom and Colonies on a person who was born before 6 December in the 26 counties but was domiciled outside those counties on 6 December 1922 was ordinarily resident outside the Republic of Ireland from 1935 to 1948 and was not registered as an Irish citizen under Irish legislation.
The 1949 Act confirmed that citizens of the Republic of Ireland would be treated in the same way as Commonwealth citizens and would not be treated as aliens.
British Nationality Act 1981
The British Nationality Act 1981 kept the facility by which persons born in the Republic of Ireland before 1949 could register as British subjects. British subjects retained the right to apply for registration as a British citizen after five years residence.
Irish citizens in common with Commonwealth citizens could apply for naturalisation rather than registration after five years residence. This is three years if married or in a civil partnership with a British citizen. An Irish citizen who naturalised as a British citizen may retain Irish citizenship.
Under the 1981 Act, anyone born in the United Kingdom whose parent was a British citizen or was settled in the United Kingdom was automatically a British citizen by birth. Irish citizens are deemed settled in the United Kingdom for this purpose.