In a vote of 52 percent against 48 percent, Britons on June 23, 2016, choose to end their 43-year membership of the EU.
The following day, Conservative Prime Minister David Cameron, who called the referendum and led the campaign to remain within the EU, resigns as a result of the shock vote.
In the race to replace him, Brexit campaigner Boris Johnson withdraws at the last minute and Theresa May, Cameron’s interior minister for six years, becomes prime minister on July 11.
On January 17, 2017, May gives a major speech setting out her Brexit strategy, including Britain’s exit from Europe’s single market.
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.
In a letter to EU President Donald Tusk on March 29, the government formally announces the intention to leave, setting in motion Article 50.
Its two-year timetable for withdrawal is set to wind up by March 29, 2019.
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.
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 be able to govern.
The issue of British guarantees to keep an open border between Northern Ireland and the Republic of Ireland after Brexit becomes a key sticking point in negotiations.
On December 4, May is on the cusp of an agreement but the DUP scuppers the deal at the last minute.
Britain and the EU reach a deal on some key terms of the divorce in early December 2017 after all-night negotiations. They include Britain’s EU bill as part of the settlement.
EU leaders give the go-ahead for the next stage of Brexit talks, which will include 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, following months of debate and after receiving the formal assent of Queen Elizabeth II.
The bill transfers decades of European law onto British statute books and enshrines “Brexit day” as March 29, 2019.
On July 6, May wins agreement from her cabinet to pursue “a UK-EU free trade area” that would retain a strong alignment with the EU after Brexit.
Two days later, Davis, the eurosceptic Brexit minister, quits, as does his deputy. May is giving “too much away too easily”, Davis says.
In a major blow, Foreign Secretary Boris Johnson also resigns on July 9.
The ministers “do not agree” on the best way forward in the negotiations, May admits in parliament.
On the day of Johnson’s departure, May appoints Jeremy Hunt as foreign secretary. Earlier in the day, the prime minister’s office announced the appointment of Dominic Raab as Brexit secretary.
In his resignation letter, Johnson claims the country “was headed for the status of colony.”
“The dream is dying, suffocated by needless self-doubt,” Johnson writes in the letter to May.
I am proud to have served as Foreign Secretary. It is with sadness that I step down: here is my letter explaining why. pic.twitter.com/NZXzUZCjdF
— Boris Johnson (@BorisJohnson) July 9, 2018