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 The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century.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.
Administrative counties of Ireland
Administrative counties were a unit of local government created by an Act of the Parliament of the United Kingdom for use in Ireland in 1899. Following the separation of the Irish Free State from the United Kingdom of Great Britain and Ireland, administrative counties continued in use in the two parts of the island of Ireland under their respective sovereign jurisdictions. They continued in use until 1973 in Northern Ireland and until 2002 in the Republic of Ireland.