Senedd in the context of "Monmouth (Senedd constituency)"

Parliamentary sovereignty is a longstanding concept central to the functioning of the constitution of the United Kingdom, but which is also not fully defined and has long been debated. Since the subordination of the monarchy under parliament, and the increasingly democratic methods of parliamentary government, there have been the questions of whether parliament holds a supreme ability to legislate and whether or not it should.

Parliamentary sovereignty is a description of the extent to which the Parliament of the United Kingdom has absolute and unlimited power. It is framed in terms of the extent of authority that parliament holds, and whether there are any sorts of law that it cannot pass. In other countries, a written constitution often binds the parliament to act in a certain way, but there is no codified constitution in the United Kingdom. In the United Kingdom, parliament is central to the institutions of state. The concept is exclusive to the UK Parliament and therefore does not extend to the Scottish Parliament, the Senedd and the Northern Ireland Assembly.

Wales (Welsh: Cymru [ˈkəmrɨ] ) is a country that is part of the United Kingdom. Located on the island of Great Britain, it is bordered by the Irish Sea to the north and west, England to the east, the Bristol Channel to the south, and the Celtic Sea to the south-west. As of 2021, it had a population of 3.2 million. It has a total area of 21,218 square kilometres (8,192 sq mi) and over 2,700 kilometres (1,680 mi) of coastline. It is largely mountainous with its higher peaks in the north and central areas, including Snowdon (Yr Wyddfa), its highest summit. The country lies within the north temperate zone and has a changeable, maritime climate. Its capital and largest city is Cardiff.

A distinct Welsh culture emerged among the Celtic Britons after the Roman withdrawal from Britain in the 5th century, and Wales was briefly united under Gruffudd ap Llywelyn in 1055. After over 200 years of war, the conquest of Wales was completed by King Edward I of England in 1283, though Owain Glyndŵr led the Welsh Revolt against English rule in the early 15th century, and briefly re-established an independent Welsh state with its own national parliament (Welsh: senedd). In the 16th century the whole of Wales was annexed by England and incorporated within the English legal system under the Laws in Wales Acts 1535 and 1542. Distinctive Welsh politics developed in the 19th century. Welsh Liberalism, exemplified in the late 19th and early 20th century by David Lloyd George, was displaced by the growth of socialism and the Labour Party. Welsh national feeling grew over the century: a nationalist party, Plaid Cymru, was formed in 1925, and the Welsh Language Society in 1962. A governing system of Welsh devolution is employed in Wales, of which the most major step was the formation of the Senedd (Welsh Parliament, formerly the National Assembly for Wales) in 1998, responsible for a range of devolved policy matters.

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.

England and Wales (Welsh: Cymru a Lloegr) is one of the three legal jurisdictions of the United Kingdom. It covers the constituent countries England and Wales and was formed by the Laws in Wales Acts 1535 and 1542. The substantive law of the jurisdiction is English law.

The devolved Senedd (Welsh Parliament; Welsh: Senedd Cymru) – previously named the National Assembly for Wales – was created in 1999 under the Government of Wales Act 1998 and provides a degree of self-government in Wales. The powers of the legislature were expanded by the Government of Wales Act 2006, which allows it to pass its own laws, and the Act also formally separated the Welsh Government from the Senedd. There is currently no equivalent body for England, which is directly governed by the parliament and government of the United Kingdom.

Cardiff (/ˈkɑːrdɪf/ ; Welsh: Caerdydd [kairˈdiːð, kaːɨrˈdɨːð] ) is the capital and largest city of Wales. Cardiff had a population of 383,919 in 2024 and forms a principal area officially known as the City and County of Cardiff (Welsh: Dinas a Sir Caerdydd). The city is the eleventh largest in the United Kingdom. Located in the southeast of Wales and in the Cardiff Capital Region, Cardiff is the county town of the historic county of Glamorgan and in 1974–1996 of South Glamorgan. It belongs to the Eurocities network of the largest European cities. A small town until the early 19th century, its prominence as a port for coal when mining began in the region helped its expansion. In 1905, it was ranked as a city and in 1955 proclaimed capital of Wales. The Cardiff urban area covers a larger area outside the county boundary, including the towns of Dinas Powys and Penarth.

Cardiff is the main commercial centre of Wales as well as the base for the Senedd, the Welsh Parliament. At the 2021 census, the unitary authority area population was put at 362,400. The population of the wider urban area in 2011 was 479,000. In 2011, it ranked sixth in the world in a National Geographic magazine list of alternative tourist destinations. It is the most popular destination in Wales with 21.3 million visitors in 2017. It was voted as the best city in the UK at the 2023 Readers' Choice Awards.

The fifth periodic review of Westminster constituencies was undertaken between 2000 and 2007 by the four boundary commissions for England, Scotland, Wales and Northern Ireland for the UK Parliament. The changes for England, Wales and Northern Ireland took effect at the 2010 general election; that for Scotland took effect at the 2005 election. Changes were also made to the constituencies and electoral regions of the then National Assembly for Wales (now the Senedd), and took effect at the 2007 Assembly election. All of the recommendations were approved.

In the United Kingdom, devolution (historically called home rule) is the Parliament of the United Kingdom's statutory granting of a greater level of self-government to parts of the United Kingdom, such as to Scotland, Wales, Northern Ireland and parts of England, specifically to London and the combined authorities.

Statutory powers have been awarded to the Scottish Parliament, the Senedd (Welsh Parliament), and the Northern Ireland Assembly, with authority exercised by their associated executive bodies: the Scottish Government, Welsh Government, and Northern Ireland Executive respectively. In England, oversight powers and general responsibility have also been given to the London Assembly, which oversees the Greater London Authority and Mayor of London; and, since 2011, various mayoral combined authorities throughout England. There have been further proposals for devolution in England, including national devolution, regional devolution (such as to northern England or Cornwall) or failed proposals for regional assemblies.

Politics in Wales forms a distinctive polity in the wider politics of the United Kingdom, with Wales as one of the four constituent countries of the United Kingdom (UK).

Constitutionally, the United Kingdom is a unitary state with one sovereign parliament delegating power to the devolved national parliaments, with some executive powers divided between governments. Under a system of devolution adopted in the late 1990s three of the four countries of the United Kingdom, Wales, Scotland and Northern Ireland, voted for limited self-government, subject to the ability of the UK Parliament in Westminster, nominally at will, to amend, change, broaden or abolish the national governmental systems. As such, the Senedd (Welsh Parliament; Welsh: Senedd Cymru) is not de jure sovereign. Since then, further Welsh devolution has granted the Senedd additional powers.

Plaid Cymru (English: /plaɪd ˈkʌmri/ plyde KUM-ree, Welsh: [plaid ˈkəmrɨ]; lit. 'Party of Wales', officially Plaid Cymru – the Party of Wales, and often referred to simply as Plaid) is a centre-left, Welsh nationalist political party in Wales, committed to Welsh independence from the United Kingdom. It campaigns on a platform of social democracy and civic nationalism. The party is a supporter of the European Union and is a member of the European Free Alliance (EFA). The party holds 4 of 32 Welsh seats in the UK House of Commons, 14 of 60 seats in the Senedd, and 200 of 1,234 principal local authority councillors. Plaid was formed in 1925 under the name Plaid Genedlaethol Cymru ('the national party of Wales') and Gwynfor Evans won the first Westminster seat for the party at the 1966 Carmarthen by-election.

In 1999 (in the first devolved Welsh Assembly election), Plaid Cymru gained considerable ground in traditionally Labour heartlands. These breakthroughs were part of the intentional aim to win more seats in the Welsh valleys and North East Wales, which continues to be an ambition today. The party have mostly been in opposition in the Senedd. Although under the leadership of Ieuan Wyn Jones, the party was part of a coalition as a junior partner with Welsh Labour (See: One Wales, Morgan and Jones governments) between 2007 and 2011. Wyn Jones became the deputy First Minister and Minister for the Economy and Transport, other Plaid Cymru Assembly members were also part of the cabinets.