Northern Ireland

Northern Ireland was a country situated on the island of Ireland. It was one of four countries in the United Kingdom, in addition to those of Great Britain.

History
In 1879, Victoria was Queen of the "United Kingdom of Great Britain and Ireland." (TV: Tooth and Claw) Later, the nation was known as the "United Kingdom of Britain and Northern Ireland", as stated by the Eleventh Doctor (TV: The Beast Below) while John Frobisher, in 2009, identified himself as Permanent Secretary to the Home Office of "the United Kingdom and Northern Ireland." (TV: Children of Earth: Day Three)

Following the Second World War, Northern Ireland kept the British Army "busy" during the remainder of the 20th century. (PROSE: The Dying Days)

During the 1970s, the Irish Republican Army was active in Northern Ireland. (PROSE: Who Killed Kennedy)

Callum Fitzhaugh was from Derry in Northern Ireland, as was his girlfriend Caitlin. After being rejected by Caitlin in 1999, Callum's distress allowed the Mandragora Helix to take him over and turn him into the businessman Dara Morgan, who employed a number of Northern Irish people, including Caitlin, at MorganTech. (PROSE: Beautiful Chaos)

It was still a part of the UK in the 33rd century, when the British population bar Scotland inhabited Starship UK. (TV: The Beast Below)

Behind the scenes
BBC One Northern Ireland has its own continuity announcement which was subject to a Cyberman interruption preceding The Doctor Falls.