Revenue stamps of Northern Ireland
Upon the partition of Ireland in 1921, separate revenue stamps began to be issued for both Northern Ireland and Southern Ireland. The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century. The need for separate issues for Northern Ireland came about since taxes raised there were meant to remain in the country. Most Northern Irish revenue stamps were British key types with appropriate inscriptions, but there were a number of different issues as well.
Partition of Ireland
Soon after the end of the war Sinn Féin won the overwhelming majority of the Irish parliamentary seats in the UK general election of 1918, and in January 1919 the Sinn Féin members declared unilaterally an independent (all-island) Irish Republic. Unionists, however, won a majority of seats in four of the nine counties of Ulster and affirmed their continuing loyalty to the United Kingdom. Following the Paris Peace Conference, in September 1919 Lloyd George tasked the "Long Committee" to implement Britain's commitment to introduce Home Rule, which was based on the policy of Walter Long, and some findings of the Irish Convention. The result was to be two home-rule Irish jurisdictions, and in November 1920 the Government of Ireland Act 1920 was enacted. As a result of this, in April 1921 the island was partitioned into Southern and Northern Ireland.