Brexit. Summary.

The United Kingdom European Union membership referendum, also known as the EU referendum and the Brexit referendum, took place on 23 June 2016 in the United Kingdom (UK) and Gibraltar to ask the electorate if the country should remain a member of, or leave the European Union (EU), under the provisions of the European Union Referendum Act 2015 and also the Political Parties, Elections and Referendums Act 2000. The referendum resulted in 51.9% of votes being in favour of leaving the EU. Although legally the referendum was non-binding, the government of that time had promised to implement the result, and it initiated the official EU withdrawal process on 29 March 2017, meaning that the UK was due to leave the EU before 11PM on 29 March 2019, UK time, when the two-year period for Brexit negotiations expired.[1]

Membership of the EU and its predecessors has long been a topic of debate in the United Kingdom. The country joined what were then the three European Communities, principally the European Economic Community (EEC, or "Common Market"), in 1973. A previous referendum on continued membership of the then European Communities (Common Market) was held in 1975, and it was approved by 67.2% of those who voted.

In May 2015, in accordance with a Conservative Party manifesto commitment following their victory at the 2015 UK general election, the legal basis for a referendum on EU membership was established by the UK Parliament through the European Union Referendum Act 2015. Britain Stronger in Europe was the official group campaigning for the UK to remain in the EU, and was endorsed by the Prime Minister David Cameron and Chancellor George Osborne. Vote Leave was the official group campaigning for the UK to leave the EU, and was fronted by the Conservative MP Boris Johnson, Secretary of State for Justice Michael Gove and Labour MP Gisela Stuart. Other campaign groups, political parties, businesses, trade unions, newspapers and prominent individuals were also involved, and each side had supporters from across the political spectrum.

Immediately after the result, financial markets reacted negatively worldwide, and Cameron announced that he would resign as Prime Minister and Leader of the Conservative Party, having campaigned unsuccessfully for a "Remain" vote. It was the first time that a national referendum result had gone against the preferred option of the UK Government. Cameron was succeeded by Home Secretary Theresa May on 13 July 2016. The opposition Labour Party also faced a leadership challenge as a result of the EU referendum. Several campaign groups and parties (supporting both leave and remain) have been fined by the Electoral Commission for campaign finance irregularities, with the fines imposed on Leave.EU and BeLeave constrained by the cap on the commission's fines. There is also an ongoing investigation into possible Russian interference in the referendum.[]