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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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.
Scottish independence
The United Kingdom of Great Britain and Ireland was formed by the Acts of Union 1800, which united the Kingdom of Great Britain and the Kingdom of Ireland. The 26 southern counties of Ireland left the Union in 1922, which became known as the United Kingdom of Great Britain and Northern Ireland.