Justine Greening has become the most senior Conservative MP to give her support to a second referendum on EU membership. Here are some of the questions being asked about a “People’s Vote”:

Justine Greening tweet Justine Greening took to Twitter (Screengrab/PA)

– Who else backs a second referendum?

The Liberal Democrats and Greens are demanding a vote on the final Brexit deal, with the option of remaining in the EU, along with campaign groups Best for Britain and People’s Vote and former political leaders like Tony Blair, Sir John Major, David Miliband, Nick Clegg and Lord Heseltine.

– What about Labour?

Jeremy Corbyn’s party is keeping its options open. Despite polls suggesting a majority of party members would back a second vote, Labour is not calling for one, though it has not ruled it out. Equally, the Scottish National Party, currently the third party in Westminster, has left the option of a referendum on the table.

– And what do Brexiters think of it?

Leavers’ standard response is to say the issue was settled with the 52%-48% vote in favour of Brexit in 2016. They say calls for a second referendum are just another example of the EU forcing voters to go back to the polls until they get the “right” result.

However, former Ukip leader Nigel Farage has flirted with the idea of a second poll, suggesting it might be necessary to “kill off” the idea of continued membership.

– And the Government?

Theresa May’s official spokesman says: “The British people have voted to leave the EU and there is not going to be a second referendum under any circumstances.”

– What do the polls tell us?

Over the past year, opinion surveys have fairly consistently shown voters think Britain made the wrong decision in 2016. But until recently this has not been matched by any appetite to re-run the referendum. Polls over the past few months appear to have shown a shift in opinion towards a decisive second vote.

Public opinion of Brexit negotiations(PA Graphics)

– What would the question be?

This is the crucial issue. Remainers insist voters should be offered a choice between whatever deal the Government has secured and staying in the EU. Brexiters say the decision to leave has already been taken, so the ballot paper should offer the options of leaving under the Government deal or with no deal. Ms Greening wants to offer three options, with voters given first and second preferences.

– Would that settle the question at last?

Highly unlikely. Victory for Remain would leave Brexiters howling betrayal and leave huge numbers of voters feeling their views had been ignored. A vote for a no-deal departure would horrify Remainers and potentially cause panic in the business community.

The Government’s compromise deal might well be knocked out on the second count, even though it might have beaten either of the other options when second preferences were taken into account.

– So will a second referendum happen?

It’s very difficult to say. The decision may well lie in Jeremy Corbyn’s hands. If he is willing to whip his MPs to vote for one, it is quite possible that enough Tories would rebel to force Theresa May to accept it. But it is far from clear that the Labour leader is ready to accept a second vote. Much will depend on how public opinion moves in the face of open warfare within the Conservatives over the PM’s Chequers deal.

– And would the EU accept the result?

Brussels has repeatedly sent signals that it would be ready to discard Britain’s Article 50 letter if the UK changed its mind. However, Brexiters warn that the EU would demand concessions – such as an end to the British rebate or maybe even a promise to join the euro – in return for writing off the last two years of disruption over Brexit.