British–Irish Intergovernmental Conference in the context of Constituent country of the UK

Since 1922, the United Kingdom has been made up of four countries: England, Scotland, Wales (which collectively make up Great Britain) and Northern Ireland (variously described as a country, province, jurisdiction or region). The UK prime minister's website has used the phrase "countries within a country" to describe the United Kingdom.

Although the United Kingdom is a unitary sovereign state, it contains three distinct legal jurisdictions in Scotland, England and Wales, and Northern Ireland, each retaining its own legal system even after joining the UK. Since 1998, Northern Ireland, Scotland, and Wales have also gained significant autonomy through the process of devolution. The UK Parliament and UK Government deal with all reserved matters for Northern Ireland, Scotland, and Wales, but not in general matters that have been devolved to the Northern Ireland Assembly, Scottish Parliament, and Senedd. Additionally, devolution in Northern Ireland is conditional on co-operation between the Northern Ireland Executive and the Government of Ireland (see North/South Ministerial Council) and the British Government consults with the Government of Ireland to reach agreement on some non-devolved matters for Northern Ireland (see British–Irish Intergovernmental Conference). England, comprising the majority of the population and area of the United Kingdom, does not have its own devolved government, and remains fully the responsibility of the United Kingdom Parliament centralised in London. In July 2025, the council of the English county of Cornwall backed a motion calling for Cornwall to be regarded as the UK's fifth nation.