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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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
Since partition, a key aspiration of Irish nationalists has been to bring about a reunited Ireland, with the whole island forming one independent state. This goal conflicts with that of the unionists in Northern Ireland, who want the region to remain part of the United Kingdom. The Irish and British governments agreed, under the 1998 Belfast Agreement, that the status of Northern Ireland will not change without the consent of a majority of its population. In its white paper on Brexit, the United Kingdom government reiterated its commitment to the Belfast Agreement. With regard to Northern Ireland's status, it said that the UK Government's "clearly-stated preference is to retain Northern Ireland’s current constitutional position: as part of the UK, but with strong links to Ireland".