A chronology of key events:
1801 – United Kingdom formed by union of the kingdoms of Great Britain and Ireland.
1815 – Role in defeating Napoleon's French Empire leads to Britain becoming pre-eminent imperial power.
1830s – Electoral reform acts begin steady move towards primacy of House of Commons and universal suffrage.
1840s – British industrial power harnessing technological change and boosts free trade and investment worldwide, reaching its peak in the second half of the 19th century.
1880s – Devolved government for Ireland becomes a major political issue, splitting Liberal Party and reviving a violent Irish separatist movement.
1904 – Entente Cordiale with France marks Britain's return to European security treaties.
1906 – Liberal government lays foundations for later welfare state with pensions, work and sickness insurance and the expansion of secondary education.
1914 – Outbreak of First World War. UK enters hostilities against Germany. Gruelling trench warfare in Belgium and France.
1918 – War ends in November with armistice. The number of UK war dead runs to several hundred thousand.
1921 – UK agrees to the foundation of the Irish Free State after three-years Irish war of independence. Northern Ireland remains part of the UK.
1924 – First government led by the Labour Party under Ramsay MacDonald.
1926 – General Strike arising from coal dispute.
1929 – World stock market crash. Unemployment begins to rise in UK.
1931 – Economic crisis. Millions are unemployed. National Government coalition formed.
1936 – King Edward VIII abdicates over relationship with an American divorcee, Wallis Simpson.
1938 – Prime Minister Neville Chamberlain meets the leader of Nazi Germany, Adolf Hitler, in Munich. Chamberlain says he has averted war with Germany.
1939 – Germany invades Poland. UK declares war on Germany.
1940 – Winston Churchill becomes prime minister. Fighter pilots repel German air attacks in the Battle of Britain. London and other cities badly damaged in German bombing raids.
1944 – Allied troops invade France from Britain on D-Day (6th June) and begin to fight their way towards Germany.
1945 – Germany surrenders on 8 May.
Labour leader Clement Atlee wins landslide election victory.
Decolonisation and new responsibilities
1945 – The UK becomes a permanent member of the UN Security Council.
1947 – The former colony of India becomes independence.
1948 – National Health Service is established.
1949 – The UK becomes a founder member of Nato.
1956 – UK intervenes in Suez Canal Zone, but withdraws under pressure from the US.
1961 – UK application to join European Economic Community vetoed by French President Charles de Gaulle.
1969 – British troops sent to quell unrest in Northern Ireland.
1973 – The UK joins the European Economic Community.
Industry on a three-day week because of strike by power workers and miners.
1975 – EEC membership is endorsed in a referendum. North Sea oil begins to be pumped ashore.
1979 – The Conservative politician Margaret Thatcher becomes prime minister. She begins to introduce free-market policies.
1981 – Government begins programme of privatisation of state-run industries, followed by deregulation of financial markets.
1982 – Argentina invades the Falklands Islands in the South Atlantic. The UK dispatches a task force, which re-takes them.
1984 – The IRA attempts to assassinate Margaret Thatcher in her hotel in Brighton. Several killed and injured by a bomb blast, but the prime minister escapes unhurt.
1990 – Mrs Thatcher resigns as prime minister after she fails to defeat a challenge to her leadership of the Conservative party. John Major becomes prime minister.
1991 – UK takes part in US-led military campaign to liberate Kuwait from Iraqi occupation.
1992 – John Major re-elected as prime minister.
1993 – Downing Street declaration on Northern Ireland – a peace proposal issued jointly with the Irish government.
1996 – Government announces that BSE, or 'mad cow disease', can be transmitted to humans. Crisis for beef industry follows, with mass slaughtering of animals, collapse of markets and export bans. Many beef farmers face financial ruin.
1997 May – Labour Party under Tony Blair wins landslide election victory.
1997 August – Diana, Princess of Wales, is killed in a car crash in Paris.
1997 September – Referendums in Scotland and Wales back the creation of separate assemblies, which are inaugurated in 1999.
1998 – Good Friday Agreement on a political settlement for Northern Ireland is approved by voters in the Republic of Ireland and Northern Ireland.
1999 – UK forces take part in the air war against Yugoslavia and the consequent multinational force in Kosovo.
2000 May – UK forces intervene in Sierra Leone to protect and evacuate foreign citizens caught up in the civil war. They subsequently stay on to help train the government army.
2001 January – Libyan intelligence agent Abdelbaset al-Megrahi is found guilty of the 1988 bombing of Pan Am Flight 103 over Lockerbie in Scotland. All 259 people on board as well as 11 on the ground were killed.
2001 September/November – Following September 11 attacks on targets in the US, PM Tony Blair offers strong support for US-led campaign against international terrorism. British forces take part in air strikes on targets in Afghanistan.
2003 March – UK joins US-led military campaign against Iraq after UN-based diplomatic efforts to ensure Baghdad has no weapons of mass destruction are perceived to have failed.
2004 January – Lord Hutton delivers findings of inquiry into suicide of government scientist David Kelly, who had expressed concern about UK intelligence on Iraq's weapons of mass destruction programme to the BBC. His report exonerates the government, heavily criticises the BBC.
2005 7 July – 52 people are killed and around 700 are injured in four Islamist suicide bomb attacks on London's transport network. Two weeks later, more would-be bombers fail to detonate four devices on same network.
2005 July – Irish Republican Army (IRA) announces formal end to its armed campaign.
2007 May – Leaders of Northern Ireland Assembly sworn in, ending five years of direct rule from London.
Pro-independence Scottish National Party (SNP) becomes the largest party in the Scottish Parliament following elections.
2007 June – Gordon Brown succeeds Tony Blair as prime minister and Labour leader.
2007 July – Diplomatic row with Russia over Britain's bid to extradite Andrei Lugovoi, an ex-KGB agent accused of killing Russian defector Alexander Litvinenko in London with radioactive polonium.
2008 October – The government part-nationalises three leading UK banks with a 37 billion pound rescue package. It also pumps billions into the UK financial system after record stock market falls precipitated by the global "credit crunch".
2009 November – Britain withdraws bulk of its remaining troops in southern Iraq, leaving only a small force tasked with training the Iraqi military.
The UK economy comes out of recession, after figures show it grew by 0.1% in the last quarter of 2009, following six consecutive quarters of economic contraction – the longest such period since quarterly figures were first recorded in 1955.
2010 May – General election: Conservative Party wins most seats but fails to gain an absolute majority. Conservative leader David Cameron heads first post-war coalition with the third-placed Liberal Democrats.
2010 October – Coalition announces large-scale public spending cuts aimed at reducing UK's budget deficit, with an average 19% four-year cut in budgets of government departments.
2011 March-September – Britain plays a prominent part in the international intervention in the conflict in Libya.
2011 May – Referendum rejects plan to replace first-past-the-post electoral system for House of Commons with alternative vote proportional system. 2011 August – The killing of a 29-year old man by police sparks widespread riots and looting in poorer areas of London, as well as in several other English cities. Insurers estimate the cost of the damage at more than £200m.
2011 December – Prime Minister David Cameron blocks proposed changes to the EU's Lisbon Treaty aimed at addressing the crisis in the eurozone, over threats to the independence of the City of London as a financial centre.
2012 August-September – Britain hosts the 2012 Summer Olympics and Paralympics to widespread international acclaim.
2012 October – British and Scottish governments agree on terms for a Scottish referendum on independence in autumn 2014.
2013 January – Prime Minister David Cameron proposes a referendum on whether to leave the European Union after the next election.
2013 May – A soldier, Drummer Lee Rigby, is hacked to death in south London by two Islamic extremists.
2013 July – The Duchess of Cambridge gives birth to a son George, who is third in line to the throne after the Prince of Wales and the Duke of Cambridge.
2013 August – The House of Commons votes to block UK military involvement in Syria in a political embarrassment for the government.
2014 May – Support for the anti-EU UK Independence Party (UKIP) surges in local and European elections.
2014 September – Voters in a referendum in Scotland reject independence, with 55% opting to remain part of the United Kingdom and 45% favouring independence.
2015 May – Conservative Party confounds polls by winning majority in general election for first time since 1992. Liberal Democrat coalition partners lose all but eight seats. UK Independence Party wins nearly four million votes, but retains only one of two seats won at by-elections.
Scottish National Party wins all but three seats in Scotland, becoming third largest party in parliament and dealing heavy blow to opposition Labour Party.
Vote to leave European Union
2016 June – Political crisis after voters in a referendum opt to quit the European Union. David Cameron resigns, succeeded as prime minister by his home secretary, Theresa May.
2017 March – Islamist Khalid Masood kills five people, including a police officer, in a rampage that ends in a thwarted attempt to force entry into parliament.
2017 May-June – Islamist attacks in Manchester and London leave a total of 30 people dead.
2017 June – Early elections, called by Prime Minister Theresa May to strength her hand in negotiating Britain's exit from the European Union, results in a hung parliament and a fragile Conservative minority government, kept in office by an agreement with the main pro-British party in Northern Ireland, the Democratic Unionists.
Formal negotiations begin to end Britain's membership of the European Union.
2018 March – Diplomatic row breaks out with Russia over poisoning of ex-spy Sergei Skripal and his daughter Yulia in Salisbury, for which Britain blames the Kremlin.
2018 July – Two key ministers, including Foreign Secretary Boris Johnson, resign in protest at government's plans for a free trade area with the European Union.
2019 December – Boris Johnson wins convincing majority at snap general election after succeeding Theresa May as prime minister in July. Britain leaves the European Union the following month.
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United Kingdom profile – Timeline – BBC
A chronology of key events: