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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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.
Civil rights movements
Northern Ireland is a part of the United Kingdom which has witnessed violence over many decades, known as the Troubles, arising from tensions between the British (Unionist, Protestant) majority and the Irish (Nationalist, Catholic) minority following the Partition of Ireland in 1920.