Brexit — a contraction of “British exit” — was the UK’s departure from the European Union, decided by referendum on 23 June 2016 and completed on 31 January 2020. It was the most consequential British political event since the Second World War, and it remains the most divisive.
The vote
Leave won by 51.9% to 48.1% on a 72% turnout — around 1.3 million votes in a poll of over 33 million. Prime Minister David Cameron, who had called the referendum to settle a long-running argument within his own party, resigned the following morning.
The split was geographic and demographic. England and Wales voted leave; Scotland and Northern Ireland voted remain, Scotland by 62%. London voted remain heavily while much of the rest of England voted leave. Younger voters and graduates leaned remain; older voters and non-graduates leaned leave. Those divisions have shaped British politics ever since.
Why people voted leave
The main drivers were sovereignty — “take back control”, the most effective political slogan in modern British history — immigration, and a broader sense in post-industrial areas of having been left behind by decades of economic change. Contributions to the EU budget featured heavily, including a much-disputed claim about £350 million a week.
Why it took four and a half years
Because the referendum asked whether to leave, not how. There was no agreed model of what leaving meant, and Parliament — where a majority of MPs had backed remain — could not agree on one. Theresa May negotiated a withdrawal agreement and lost the vote on it three times, once by 230 votes, the largest government defeat in parliamentary history. She resigned in 2019.
Boris Johnson renegotiated, called a general election on the slogan “Get Brexit Done”, won a majority of 80, and the UK left on 31 January 2020, with a transition period to the end of that year.
The Irish problem
The hardest issue, and the one that broke every proposed solution. The Good Friday Agreement depended on an invisible border between Northern Ireland and the Republic. Leaving the EU customs union meant a customs border had to exist somewhere.
The eventual answer put it in the Irish Sea, keeping Northern Ireland aligned with EU goods rules. Unionists regarded this as a border within the United Kingdom, and the resulting dispute collapsed power-sharing at Stormont for two years.
What changed
Freedom of movement ended in both directions. British citizens can visit the EU visa-free for 90 days in any 180 but no longer have an automatic right to live or work there. Customs checks and paperwork returned for goods. EU nationals already in the UK were given settled status.
Where opinion stands
Polling has moved. Consistent majorities now say leaving was the wrong decision, though there is no comparable majority for rejoining, and neither main party proposes it. Brexit is best understood in Britain now not as a live policy debate but as a settled fact that people continue to feel very strongly about.