Revenue stamps of the United Kingdom
When Ireland was partitioned into Northern Ireland and Southern Ireland in 1921, separate revenue stamps were issued for both entities. Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps). However, Northern Ireland continued to use separate revenue stamps until the 1980s. Northern Irish revenues include Civil Service, Dog Licence, Excise and National Insurance stamps, among many others.
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.