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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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.
Monarchy of the United Kingdom
In 1800, as a result of the Irish Rebellion of 1798, the Act of Union merged the kingdom of Great Britain and the kingdom of Ireland into the United Kingdom of Great Britain and Ireland. The whole island of Ireland continued to be a part of the United Kingdom until 1922, when what is now the Republic of Ireland won independence as the Irish Free State, a separate Dominion within the Commonwealth. The Irish Free State was renamed Éire (or "Ireland") in 1937, and in 1949 declared itself a republic, left the Commonwealth and severed all ties with the monarchy. Northern Ireland remained within the Union. In 1927, the United Kingdom changed its name to the United Kingdom of Great Britain and Northern Ireland, while the monarch's style for the next twenty years became "of Great Britain, Ireland and the British Dominions beyond the Seas, King, Defender of the Faith, Emperor of India".