Listen to this article
October 2011 David Cameron suffered a rebellion by 81 Tory MPs seeking a referendum on EU membership. Although they were easily defeated, the size of the uprising emphasised the scale of the prime minister’s European problem.
January 2013 Mr Cameron capitulated and promised an EU referendum, saying the British people must “have their say” on Europe with an In/Out referendum if the Conservatives won the general election. This would follow a renegotiation of the UK’s relationship with the bloc.
Nov 8 2015 The prime minister declared that Britain was no longer “the sick man of Europe” that it was in the 1970s and could continue to thrive outside of the EU. He said that Britain could be successful in or out of Europe and that voters must make a judgment based on the reforms he would secure.
Feb 20 2016 The PM returned from his renegotiation talks, insisting he had secured a string of reforms. He announced at Downing Street that the vote would take place on Thursday June 23. Within hours, Tory ministers divided up into the Leave and Remain camps.
Feb 21 Boris Johnson held an impromptu press conference outside his home in west London. The former London mayor said that “after a huge amount of heartache” he would campaign for Out.
April 13 The Tory-dominated Vote Leave group was announced as the official campaign. That angered the “Grassroots Out” Movement, which had strong links to the UK Independence party.
April 15 The referendum campaign kicked off with campaign events and rallies across the country. In still had a firm lead in the polls.
April 22 In an apparent public relations coup for Mr Cameron, US President Barack Obama issued a direct warning about the dangers of Brexit. Britain would be at the back of the queue for any future trade deal with the US, he claimed.
May 5 Elections were held for the Welsh Assembly, Scottish Parliament and Northern Ireland Assembly despite concerns that the referendum date was too soon afterwards.
May 23 The Treasury issued a dossier highlighting the potential risks to the economy from Brexit, including half a million job losses and a plunge in GDP. The Out campaign accused Chancellor George Osborne of exaggeration and alarmism.
May 27 Purdah started and the usual process of government went into the deep freeze.
June 2 Mr Cameron, who refused to do a face-to-face debate, came in for tough questioning on Sky News. On the same day, opposition leader Jeremy Corbyn, who was supposed to be in the Remain camp, said Treasury warnings about an economic downturn following a Leave vote were scaremongering.
June 3 Brexiter Michael Gove struggled to name any business backers for the Out side as he took his turn at being grilled by a Sky News panel.
June 10 After days of the Out campaign gaining strength, a poll by ORB for The Independent gave a 10-point lead for Leave.
June 15 Ukip joined fishing boats on the Thames to protest against EU fishing quotas. The stunt turned into a bizarre carnival when In campaigners led by Bob Geldof took to the waters.
June 16 In the morning, Ukip leader Nigel Farage unveiled an anti-immigration poster with a queue of mostly non-white migrants and refugees with the slogan: “Breaking Point: the EU has failed us all”.
June 16 In the afternoon the news emerged of the brutal killing of Jo Cox, a Labour MP. Campaigning was later suspended for several days.
June 21 The BBC hosted a debate on the referendum to a huge crowd at Wembley Arena. Ruth Davidson, Tory leader in Scotland, impressed commentators with a robust performance for Remain.