The Troubles
The Government of Ireland Act 1920 partitioned the island of Ireland into two separate jurisdictions, Southern Ireland and Northern Ireland, both devolved regions of the United Kingdom. This partition of Ireland was confirmed when the Parliament of Northern Ireland exercised its right in December 1922 under the Anglo-Irish Treaty of 1921 to ""opt out"" of the newly established Irish Free State. A part of the treaty signed in 1922 mandated that a boundary commission would sit to decide where the frontier of the northern state would be in relation to its southern neighbour. After the Irish Civil War of 1922–1923, this part of the treaty was given less priority by the new Dublin government led by W. T. Cosgrave, and was quietly dropped. As counties Fermanagh and Tyrone and border areas of Londonderry, Armagh, and Down were mainly nationalist, the Irish Boundary Commission could reduce Northern Ireland to four counties or less.
Irish in the British Armed Forces
After the secession of most of Ireland as the Irish Free State and the partition of Ireland, which led to the creation of Northern Ireland, the rule continued to be in place. Particularly during The Troubles, there was a climate of mutual suspicion, as some Ulster unionists regarded elements of the GAA as sympathetic in some ways to the goals of the Provisional IRA and at the same time, the GAA (especially in the North) were suspicious of Royal Ulster Constabulary personnel wishing to join. As part of the Northern Ireland peace process and the reforming of the police into a more cross-community institution, as the Police Service of Northern Ireland, moves were made to lift the ban. In 2001, during the presidency of Seán McCague, the ban was lifted, with 26 counties voting yes. Members of the Irish diaspora serving in the Irish Guards founded the "Gardaí Éireannach" as part of the London GAA in 2015.