Brexit Explained

Brexit explained in plain English means tracing how the referendum happened, what Article 50 did, and how the UK eventually left the European Union.

This guide explores the background to Brexit, the key events and the agreements that shape UK–EU relations. We distinguish established facts from interpretation, explain important terminology and provide links to primary sources wherever possible.

Our aim is to help you understand the issues, consider different perspectives and draw your own conclusions.

What Is Brexit?

Brexit is the term used to describe the United Kingdom's withdrawal from the European Union (EU). The word combines "Britain" and "exit".

On 23 June 2016, the UK held a referendum in which a majority of those who voted supported leaving the European Union. Following several years of negotiations, the UK formally left the EU on 31 January 2020.

A transition period followed, lasting until 31 December 2020. During this period, most EU rules continued to apply in the UK. On 1 January 2021, the EU–UK Trade and Cooperation Agreement began applying provisionally, establishing arrangements for trade and cooperation alongside the continuing Withdrawal Agreement.

Sources: House of Commons Library — Brexit Timeline | European Commission — EU–UK Trade and Cooperation Agreement

How Did Brexit Come About?

The UK's relationship with European integration began long before the Brexit referendum. On 1 January 1973, Britain joined the European Economic Community (EEC), commonly known as the Common Market.

Membership was debated from the outset. In June 1975, the UK held its first nationwide referendum on whether to remain in the EEC. Of those who voted, 67.2% supported continued membership, while 32.8% voted to leave.

Over the following decades, European cooperation expanded beyond the original Common Market. The Single European Act, which came into force in 1987, laid the groundwork for completing the European single market.

The Maastricht Treaty, which entered into force on 1 November 1993, formally established the European Union. It introduced additional areas of cooperation, including foreign and security policy, justice and home affairs.

Sources: UK Parliament — The EEC and the Single European Act | European Union — History 1990–99

The Road to the 2016 Referendum

During 2015, the UK government negotiated changes to its relationship with the European Union. The discussions covered four principal areas: economic governance, competitiveness, sovereignty, and free movement and social benefits.

On 18–19 February 2016, EU leaders agreed on a new settlement for the United Kingdom. The arrangements were intended to take effect if the UK voted to remain a member of the European Union.

On 20 February 2016, following a Cabinet meeting, David Cameron announced that the government would propose holding the referendum on Thursday 23 June 2016.

The agreement reached with the EU was conditional on continued UK membership. Following the referendum result, the proposed settlement did not take effect.

Sources: House of Commons Library — European Union Referendum Bill 2015–16 | European Council — Negotiations Ahead of the UK's EU Referendum | UK Government — PM Statement, 20 February 2016

The 2016 Referendum Campaign

The referendum campaign brought together political parties, campaign organisations and individuals with differing views on Britain's membership of the European Union.

On 13 April 2016, the Electoral Commission designated two official lead campaign organisations: Vote Leave, which supported leaving the European Union, and Britain Stronger in Europe, which supported remaining. Other organisations also campaigned on both sides of the debate.

The Leave campaign emphasised national sovereignty, control over immigration, the ability to make laws independently of EU institutions and the possibility of developing independent trade arrangements.

The Remain campaign emphasised the economic benefits of EU membership, access to the European single market, international cooperation and the potential economic risks of leaving. Both sides presented competing claims about Britain's future, and the accuracy and implications of particular campaign statements became subjects of public debate.

Sources: Electoral Commission — Designation of the Lead Campaigners | House of Commons Library — EU Reform Negotiations and the Tusk Package

Examining the Campaign Claims

One of Vote Leave's most prominent campaign messages concerned the UK's financial contributions to the European Union. The campaign promoted a figure of £350 million per week and suggested that money could instead be spent on the National Health Service.

On 27 May 2016, the UK Statistics Authority stated that this gross figure did not account for the UK's rebate or payments received from the EU. The Authority concluded that presenting the gross amount as money available to spend elsewhere, without explaining these adjustments, was misleading.

The Remain campaign also used economic projections to support its arguments. In April 2016, HM Treasury published an analysis estimating that, under a particular future trade arrangement, leaving the EU would reduce annual UK economic output by an amount equivalent to £4,300 per household after 15 years, compared with continued membership.

The figure was a modelled estimate of GDP per household, not a prediction that every household would lose £4,300 in disposable income. A House of Commons Treasury Committee report subsequently highlighted the importance of distinguishing these measures and explaining the uncertainties surrounding economic forecasts.

Sources: UK Statistics Authority — Statement on EU Contributions | HM Treasury — Long-term Economic Impact Analysis | House of Commons Treasury Committee — Economic and Financial Costs and Benefits of EU Membership

The Official 2016 Referendum Result

On 23 June 2016, voters across the United Kingdom and Gibraltar participated in the referendum on continued membership of the European Union. The official result was declared on 24 June 2016.

Of the valid votes cast, 17,410,742 (51.9%) supported leaving the European Union, while 16,141,241 (48.1%) supported remaining. Leave received 1,269,501 more votes than Remain.

The referendum attracted a turnout of 72.2%, with 33,577,342 ballot papers counted. There were 25,359 rejected ballot papers.

Source: Electoral Commission — Official Result of the 2016 EU Referendum

The result established a majority for leaving among those who cast valid votes. However, voting patterns differed considerably across the four nations of the United Kingdom.

Sources: House of Commons Library — Analysis of the EU Referendum Results 2016 | Electoral Commission — Report on the 23 June 2016 Referendum

How Did the Four Nations Vote?

Although the overall referendum produced a majority in favour of leaving the European Union, the results differed across the four nations of the United Kingdom.

England voted 53.4% Leave and 46.6% Remain, while Wales voted 52.5% Leave and 47.5% Remain. Scotland recorded a majority for Remain, with 62.0% voting to stay in the EU, as did Northern Ireland, where 55.8% voted Remain.

The referendum result was determined by the total number of votes cast across the United Kingdom and Gibraltar, rather than by separate majorities in each nation.

Voting patterns also varied within England. London was the only English counting region to record a Remain majority. These geographical differences became an important part of subsequent discussions about Brexit and the constitutional relationships within the United Kingdom.

Sources: House of Commons Library — Analysis of the EU Referendum Results 2016 | Electoral Commission — EU Referendum Results by Region

What Happened Immediately After the Referendum?