Brexit Took Britain Three Years to Negotiate and Five PMs to Implement

The United Kingdom voted on June 23, 2016, in a referendum on whether to leave the European Union, with the question phrased neutrally enough that it took the count to settle the headlines. Leave won 51.89 percent to Remain's 48.11 percent, on a turnout of 72.2 percent. England (excluding London) and Wales backed Leave; Scotland, Northern Ireland, London, and Gibraltar all backed Remain. Prime Minister David Cameron, who had called the referendum and led the Remain campaign, resigned the next morning.

What followed was the longest, messiest withdrawal process the EU had ever seen. Cameron's successor Theresa May invoked Article 50 of the Treaty on European Union on March 29, 2017, formally starting a two-year negotiation. Her government's negotiated withdrawal agreement was rejected by the Commons three times in 2019 — the largest parliamentary defeat in British political history on the first vote, by 230 votes. May resigned in July 2019. Boris Johnson, her successor, renegotiated parts of the deal, dissolved parliament, won a December 2019 general election with an 80-seat majority, and finally got the withdrawal agreement through.

The UK left the European Union at 23:00 GMT on January 31, 2020 — three years and five months after the referendum, six prime ministers (counting acting briefs), one snap general election, two contested party leadership races, and a 1,259-page withdrawal agreement later. An eleven-month transition period followed; the EU-UK Trade and Cooperation Agreement was signed on December 30, 2020. Most projections of medium-term economic effects since have run negative; debate about whether the negative numbers are causally Brexit's or attributable to global conditions continues.