From the shock Brexit referendum result to yesterday's momentous vote on Theresa May's unpopular divorce deal with the European Union, here are the milestones on Britain's rocky road out of the bloc after 46 years.
Britons vote to leave: In a referendum on June 23, 2016, Britons choose to end their membership of the 28-nation EU by 52 percent to 48 percent. It prompts the resignation the next day of Conservative prime minister David Cameron, who had called the referendum and led the campaign to remain in the EU.
May becomes PM: In a race to replace Cameron, key Brexit campaigner Boris Johnson does not put himself forward as expected and May, the interior minister who had backed remaining in the bloc, becomes prime minister on July 13. On January 17, 2017, May said Britain will also leave Europe's single market in order to control immigration.
Exit process triggered: On March 13, Britain's parliament gives final approval to a bill empowering May to trigger Article 50 of the EU treaty which lays out the process for leaving the union. With a letter to EU President Donald Tusk on March 29 formally announcing the intention to leave, the government sets Article 50 in motion. Its two-year timetable for withdrawal puts Britain on course to exit on March 29, 2019.
Polls gamble backfires: To capitalise on the perceived weakness of the opposition Labour party and strengthen her hand in Brexit negotiations, May calls a snap election for June 8, 2017. Her gamble backfires as the Conservatives lose their parliamentary majority. They are forced to strike a deal with Northern Ireland's Democratic Unionist Party (DUP) to govern.
First terms agreed: Britain and the EU reach an outline agreement on December 8 on three key areas of the divorce: Britain's financial settlement to the union, citizens' rights and the Irish border. EU leaders give the go-ahead for the next stage of Brexit talks, including on how Britain will continue to trade with the bloc after the split. A bill enacting the decision to leave the EU becomes law on June 26, 2018.
Top ministers quit: On July 6, 2018, May wins agreement from her warring cabinet to pursue "a UK-EU free trade area" that would retain a strong alignment with the EU after Brexit. But two days later David Davis, the eurosceptic Brexit minister, quits saying May is giving "too much away too easily". Johnson, now foreign secretary, resigns on July 9, becoming a leading critic of May's plans.
Draft deal agreed
The European Union on November 13 publishes contingency plans for a "no-deal" Brexit. But a few hours later, May's office says negotiating teams have reached a draft agreement for the divorce. On November 14, her cabinet backs the agreement. However the following day four ministers, including new Brexit secretary Dominic Raab, quit in protest. EU leaders approve the accord on November 25.
Party confidence vote: May's deal faces intense criticism in parliament over the "backstop" provision designed to prevent border checks in Ireland. On December 10, May postpones a House of Commons vote on the deal due the following day, acknowledging she faced a heavy defeat. She heads off to Europe for further talks, but EU leaders reject any substantive renegotiation. On December 12, May's survives a confidence vote brought by her own party challenging her leadership. The result meant May is immune from further internal party challenges for a year.
Parliament vote: On January 15, the House of Commons, Britain's lower house, finally gets its chance to vote on the draft withdrawal agreement that May struck with EU leaders in December. The vote is expected from 1900 GMT.