A video grab from footage broadcast by the UK Parliament's Parliamentary Recording Unit (PRU) shows Britain's Prime Minister Boris Johnson speaking at the opening of the Second Reading of the European Union (Withdrawal Agreement) "Brexit" Bill in the Hous
London: Britain's tortuous exit from the European Union has seen two UK governments fall and parliament locked in years of inconclusive debate.
Here are the milestones in Britain's battle over Brexit, whose end neared with parliament's initial approval of Prime Minister Boris Johnson's divorce deal.
Vote to leave
In a June 23, 2016 referendum Britons vote by 52 to 48 percent to leave the 28-nation EU.
Conservative party leader David Cameron, who had led the campaign to remain, resigns as prime minister the next day.
Theresa May, the interior minister who also backed remaining, becomes prime minister on July 13.
On January 17, 2017 she sets out her Brexit strategy, saying Britain will leave Europe's single market and control EU immigration.
Exit triggered
On March 29, 2017 the government triggers a two-year timetable for withdrawal with a letter to the EU Council formally announcing Britain's intention to leave.
The Brexit deadline is set for March 29, 2019.
To strengthen her hand in Brexit negotiations, May calls a snap election for June 8, 2017.
But the Conservatives lose their parliamentary majority and, to stay in power, strike a deal for support from Northern Ireland's hardline Democratic Unionist Party (DUP).
Draft deal agreed
On November 13, 2018 British and EU negotiators agree on a draft Brexit deal which is approved by EU leaders a week later.
But May faces an angry backlash from her own party over the terms due to fears it would leave Britain trapped in EU trade rules.
Rejected three times
In a first parliament vote on the deal on January 15, 2019, MPs vote 432 to 202 against -- the biggest government defeat in British parliamentary history.
The next day the government narrowly survives a no-confidence vote.
Parliament rejects the deal again on March 12.
On March 27, May promises to resign if it is adopted.
Parliament votes against it for a third time on March 29.
May quits, Johnson takes over
The EU agrees to delay Brexit until May 22 and then until October 31, 2019.
It means Britain is obliged to organise European Parliament elections on May 23, which are won by the Brexit Party of anti-EU populist Nigel Farage.
It prompts May to step down as Conservative leader on June 7.
On July 23 the party chooses Brexit figurehead Boris Johnson as its new leader. He becomes prime minister the next day.
He promises to take Britain out of the EU on October 31, with or without a deal.
MPs want more time
After progress on the crunch issue of the Northern Ireland border, British and European negotiators push on with talks and on October 17 announce agreement on a new draft divorce deal.
It is endorsed hours later by all other 27 EU members but on October 19 British MPs delay their decision, arguing they need more time to study it.
That means Johnson is obliged by law to write to the EU to ask for another delay, although he does not sign the letter.
New delay, new polls
On October 22 British MPs approve the deal in principle but reject Johnson's bid to fast-track the final accord.
To break the logjam and strengthen his grip on office, he moots a snap general election.
On October 28 EU members agree to postpone Brexit for up to three months, to January 31, 2020 at the latest.
The next day parliamentarians agree to an early general election on December 12, which Johnson's Conservatives overwhelmingly win.
The freshly-elected parliament gives its initial approval to Johnson's divorce deal on December 20, setting final confirmation for January 9.
