Related: Women The European Union Referendum Act 2015 (c. 36) was an act of the Parliament of the United Kingdom that made legal provision for a consultative referendum to be held in the United Kingdom and Gibraltar, on whether it should remain a member state of the European Union or leave the bloc altogether.

The Act gave effect to a manifesto commitment of the Conservative Party at the general election of May 2015, and was one of the most significant pieces of legislation that was passed by the 2015–17 Parliament.

On 1 January 1973, the United Kingdom and Gibraltar joined what was then known as the European Communities, under terms negotiated by the then Conservative Prime Minister Edward Heath.

[7] In accordance with British constitutional convention, specifically that of parliamentary sovereignty, accession was not subject to approval by referendum.

[5] 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.

This Act required a referendum to be held on the question of the UK's continued membership of the European Union before the end of 2017.

The referendums held in Scotland (1997), Wales (1997) and Northern Ireland (1998) are examples of this type, where opinion was tested before legislation was introduced.

In accordance with the Act and the public duty of the Electoral Commission, a guide was posted to every household in the UK and Gibraltar in the week beginning of 16 May 2016 by HM Government.

The leaflet was titled: "Why the Government believes that voting to remain in the European Union is the best decision for the UK".

[13] The Act legislated that the official referendum campaign period up until polling day would be of ten weeks' duration (which in the event ran from 15 April to 23 June 2016), with an official "purdah" period lasting four weeks (in the event running from 27 May until polling day) during which all government and public bodies were not permitted to comment or publish information specifically related to the subject of the referendum.

Each designated group had access to grants worth up to £600,000 as well as television spots and free leaflet drops.

with the responses to the question to be marked with a single (X): Remain a member of the European Union Leave the European Union and in Welsh: A ddylai'r Deyrnas Unedig aros yn aelod o'r Undeb Ewropeaidd neu adael yr Undeb Ewropeaidd?

with the responses (to be marked with a single (X)): Aros yn aelod o'r Undeb Ewropeaidd Gadael yr Undeb Ewropeaidd Originally the Bill set out the question that was to appear on ballot papers as: Should the United Kingdom remain a member of the European Union?

The local counts in the voting areas began from 22:00 BST (Western European Summer Time) on Thursday 23 June 2016 after all polling stations had closed.

[19] Also under the provisions of the Representation of the People Act 2000 postal ballots were also permitted in the referendum and were sent out to eligible voters some three weeks ahead of the vote (2 June 2016).

Residents of the Isle of Man, and the other Crown Dependencies Jersey and Guernsey, were not eligible to vote in the referendum, as those territories are not part of the UK [nor of the EU].

On Monday 22 February 2016, Parliament enacted secondary legislation to authorise the holding of the referendum on that date.

[23] The final number of eligible voters was published after 9 pm on Thursday 23 June 2016 by the Electoral Commission.

The national result was declared by Chief counting officer (CCO) and the then chair of the Electoral Commission Jenny Watson at Manchester Town Hall on Friday 24 June 2016 at 07:20 BST after all 382 voting areas and the 12 regions of the United Kingdom had declared their results.