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 The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century.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.
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.