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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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.
Northern Ireland
Events overtook the government. The pro-independence Sinn Féin won 73 of the 105 parliamentary seats in Ireland at the general election of 1918, and unilaterally established the First Dáil, an extrajudicial parliament in Ireland. Ireland was partitioned between Northern Ireland and Southern Ireland in 1921, under the terms of Lloyd George's Government of Ireland Act 1920, during the Anglo-Irish War between Irish republican and British forces. A truce was established on 11 July; the war ended on 6 December 1921 with the signing of the Anglo-Irish Treaty, which created the Irish Free State. Under the terms of the treaty, Northern Ireland would become part of the Free State unless the government opted out by presenting an address to the king, although in practice partition remained in place.