Britain's EU exit: A timeline of agonising Brexit battle

The key moments following the UK’s 2016 vote to leave the European Union

A pro-remain protester holds up a placard in protest against Brexit. AFP

From Britain's shock vote to leave the European Union in a 2016 referendum to a Christmas Eve trade deal after months of talks, Brexit has been a rocky and divisive process.

Britain becomes first nation to vote to leave the EU

In a referendum on June 23, 2016 that followed decades of arguments over Europe, Britons vote by 52 per cent to 48 per cent to become the first nation to leave the EU bloc.

Conservative leader David Cameron, who led the campaign to remain in the EU and called the vote expecting to win, resigns as prime minister the next day.

Theresa May takes the lead to exit Britain from the EU

Mr Cameron is replaced by Theresa May, the interior minister who also backed remaining in the EU.

Mrs May formally triggers the exit process on March 29, 2017, sending a notification letter to Brussels that gives Britain until March 29, 2019, to leave.

Britain and the EU agree a draft divorce bill

Ending more than a year of acrimonious talks, British and EU negotiators agree a draft divorce deal on November 13, 2018.

But May faces an angry backlash from her own Conservative party over its terms and MPs vote against the deal in the biggest government defeat in British parliamentary history.

Brussels refuses to re-negotiate.

EU extends Britain’s exit date

The EU agrees to delay Brexit until May 22 and then until October 31, 2019.

Theresa May resigns as prime minister

The European election defeat and parliament's rejection of her Brexit deal forces Mrs May to step down as Conservative leader on June 7.

Boris Johnson becomes prime minister

On July 23, party members choose Brexit figurehead Boris Johnson as their new leader. He becomes prime minister the next day.

MPs approve Brexit deal in principle

On October 22, British MPs approve in principle a new Brexit deal struck days earlier with the EU.

Brexit date faces delay

On October 28, EU members agree to postpone Brexit until January 31, 2020.

Mr Johnson's resounding win in a snap general election on December 12 eases his Brexit bill's passage through parliament on January 9, 2020.

MPs pass bill for divorce date

The divorce takes place on Friday, January 31.

An extendable transition period, during which much in the relationship will not change, is agreed up to December 31, 2020.

Difficult negotiations begin with Brussels

In March 2020, the EU and Britain began difficult negotiations on their future trade relationship, which are then broken off due to the coronavirus crisis.

Talks resume in April, without any notable progress on key sticking points.

Britain announces it doesn’t want to delay transition period

On June 12, Britain officially says it does not wish to extend its transition period beyond the end of the year.

In July, Britain and the EU agree to intensify talks with a view to meeting an October deadline for an accord, if the European and British parliaments are to have time to ratify it by the year end.

On September 8, the two sides open an eighth round of negotiations amid tensions as Mr Johnson warns that if there is no compromise by October 15 he will walk away with no deal.

Britain tries to rewrite the withdrawal agreement

To the EU's dismay, the British government the next day submits a bill to overwrite parts of the withdrawal agreement.

Negotiations pass October deadline

The October deadline comes and goes with no sign of a deal, with Johnson telling the EU there was "no point" in extending talks.

But Britain then ends days of threats to abandon the negotiations and instead agrees to redouble efforts to avert the potential economic chaos of a no-deal at the end of the year.

Britain enters into last-minute talks with the EU

Remaining key sticking points include so-called "level playing field" provisions to ensure Britain does not try to retreat from the EU's environmental or labour standards, how to arbitrate future differences, and fishing rights.

Talks extend into December, and Mr Johnson heads to Brussels to meet European Commission President Ursula von der Leyen to try to break the deadlock.

Negotiators work around the clock up to Christmas Eve to craft a legally binding text in time for parliamentary ratification on both sides of the Channel, with a deal finally struck in the afternoon.