<P> The Act required the Prime Minister to appoint the day on which the referendum should be held and, on 20 February 2016, David Cameron announced that the referendum would take place on Thursday 23 June 2016 . In the referendum, the electorate voted by 51.9% to 48.1% in favour of leaving the EU, on a 72% turnout . </P> <P> On 1 January 1973 the United Kingdom and Gibraltar joined what was then known as the European Economic Community (the Common Market), under terms negotiated by the then Conservative Prime Minister Edward Heath . In accordance with British constitutional convention, specifically that of parliamentary sovereignty, accession was not subject to approval by referendum . Both the Conservative Party and the Labour Party were divided over the issue, and the European Communities Act 1972 was passed due to sufficient Labour abstentions to counteract the number of rebel Tories . In the run - up to the UK General Election February 1974, the Labour Party manifesto promised a Referendum' on renegotiated terms', which its leader, Harold Wilson, hoped would end the division of his party . However the election proved indecisive and marked the end of Heath's premiership as Prime Minister and Wilson was forced to call a second election later in the year . After the UK General Election October 1974, the Labour Party formed a minority administration and held the referendum on continued membership the following year, which was approved by 67% of voters . </P> <P> For a few years the issue was largely settled but, with the approval by Parliament of the Single European Act, the Maastricht Treaty and the Lisbon Treaty, there were calls from eurosceptic Members of Parliament for a new UK referendum on continued membership . Conservative Party leader David Cameron announced in January 2013, in what became known as "The Bloomberg speech", a proposal to undertake a renegotiation of the terms of the UK's membership of the EU, and subsequently to hold a UK referendum on its membership of the Union . However, at the time of Cameron's speech, the Conservative Party was in Coalition government with the Liberal Democrats who, along with the Labour Party, were at the time opposed to any new referendum being held . The Conservative Party did not have an overall majority and a private members bill by Conservative MP James Wharton to legislate a in - out referendum by the end of 2017 was blocked in the House of Lords . The proposals were contained in the Conservative Party manifesto for the United Kingdom general election, 2015, in which the Conservatives won with an unexpected overall majority . Following the election, the opposition Labour Party withdrew its opposition to holding an in - out EU referendum . On the bill's second reading, on 9 June 2015, MPs voted by 544 to 53 in favour of the principle of holding a referendum with only the Scottish National Party opposing the Bill . </P> <P> The act legislated for a referendum to be held in the United Kingdom and Gibraltar on whether to remain a member of the EU, to be conducted by the Electoral Commission and overseen by an appointed "Chief Counting Officer" (CCO) and a "Deputy chief counting officer" (DCCO) who declared the final result for the United Kingdom . By regulation the act ordered the Secretary of State (in this case the Prime Minister) to appoint a date for the holding of the referendum, as long as the date was no later than 31 December 2017, and not on 5 May 2016 or 4 May 2017 . The Electoral Commission is the public body under the terms of the Political Parties, Elections and Referendums Act 2000 that was given the task to raise public awareness ahead of polling day, and to oversee the conduct of the referendum . </P>

How many mps voted for the eu referendum