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 Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps).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.
Privy Council of Northern Ireland
The Council was created in 1922 as a result of the division of Ireland into the Irish Free State and Northern Ireland. The latter remained part of the United Kingdom albeit with its own parliament. The previous Privy Council of Ireland was obsolete although never formally abolished in British law.