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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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.
Partition of Ireland
The Good Friday Agreement in 1998, was ratified by two referenda in both parts of Ireland, including an acceptance by the Republic that its claim to Northern Ireland would only be achieved by peaceful means. This was an important part of the Northern Ireland peace process that had been under way since 1993.