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 The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century.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.
Flag of Ireland
In 1921, Ireland was partitioned, with the unionist-dominated north-east becoming Northern Ireland, while later, in 1922, the remainder of Ireland left the United Kingdom of Great Britain and Ireland to form the Irish Free State. Northern Ireland continued to use the UK's Union Flag and created its Ulster Banner derivation of the flag of Ulster with a crown on top of a six-pointed star. Furthermore, for many years the tricolour was effectively banned in Northern Ireland under the Flags and Emblems (Display) Act (Northern Ireland) 1954 which empowered the police to remove any flag that could cause a breach of the peace but specified, rather controversially, that a Union Flag could never have such an effect. In 1964, the enforcement of this law by the Royal Ulster Constabulary at the behest of Ian Paisley, involving the removal of a single tricolour from the offices of Sinn Féin in Belfast, led to two days of rioting. The tricolour was immediately replaced, highlighting the difficulty of enforcing the law.