Revenue stamps of Northern Ireland
Upon the partition of Ireland in 1921, separate revenue stamps began to be issued for both Northern Ireland and Southern Ireland. The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century. The need for separate issues for Northern Ireland came about since taxes raised there were meant to remain in the country. Most Northern Irish revenue stamps were British key types with appropriate inscriptions, but there were a number of different issues as well.
Partition of Ireland
Following the start of the Troubles in Northern Ireland in 1969, the Sunningdale Agreement was signed by the Irish and British governments in 1973. This collapsed in May 1974 due to the Ulster Workers' Council strike, and the new British Prime Minister Harold Wilson considered a rapid withdrawal of the British Army and administration from Northern Ireland in 1974–75 as a serious policy option. The relevant cabinet notes remained secret until 2005.