Theresa May has spent twenty-one months negotiating the United Kingdom’s exit from the European Union. In a little over 30 minutes this evening, MPs brought all that to a juddering halt. The Prime Minister’s Withdrawal Agreement got a pasting, voted down by an unprecedented 432 votes to 202, a majority of 230 against the deal.

It’s the biggest defeat in modern parliamentary times. You have to go back 95 years to find the last time a Government suffered a defeat anywhere near this scale. Labour’s Ramsay Macdonald was Prime Minister back then, ironically of a minority Government. How Mrs May must rue calling a General Election in 2017 in order to secure a Commons majority designed to avoid precisely what happened tonight. Mrs May had claimed that her deal was the only available deal and voting it down risked putting Brexit itself in jeopardy. Many MPs will think that’s no bad thing, but in truth there appears to be no majority for anything in this House of Commons. Mrs May immediately challenged the Labour leader Jeremy Corbyn to call a motion of no confidence in her Government. He did so, and that debate and vote will now take place tomorrow. Mrs May is however, expected to win that vote. If she does a Brexit plan B will follow by next Monday, after that there are a raft of possible options – a renegotiated deal, an extension or revocation of Article 50, a second referendum, and of course a no deal Brexit.

Here’s our analysis on one of the most important Parliamentary votes in decades:

Summary

• What has happened: MPs rejected the Prime Minister’s Brexit deal in the House of Commons. Responding to the PM’s challenge the Labour leader Jeremy Corbyn has tabled a motion of no confidence in the Government in an effort to force an early election.
• What happens next: MPs will debate and vote on the confidence motion tomorrow, with that vote expected around 7pm.However, with her Democratic Unionist Party allies saying they will support the PM, it’s expected she will win the confidence vote. If she does indeed win that vote the Government will first hold cross party meetings to see if there is a consensus around a way forward, before possibly discussing any negotiable outcomes with the EU. Either way she has pledged to present MPs with a Plan B by Monday 21st January.
• Why does this matter: By calling Mr Corbyn’s bluff, and encouraging the no confidence vote, Mrs May is doing two things. She’s testing her partnership with the DUP, and in the event of victory, she’s forcing the hand of her Labour opponents. Jeremy Corbyn wants a general election. That can only happen if he wins the confidence vote. If he doesn’t, he will face internal Labour pressure to back a second referendum, something he abhors.

What has Happened?

• The Prime Minister has seen MPs resoundingly reject her Brexit Plan. In a defeat of historic proportions, the Prime Minister has set a new record, for all the wrong reasons. The last time a Government lost by over 100 votes was 95 years ago, and no Government has ever lost a vote by as large a margin as we saw tonight.
• Following the vote, Mrs May’s challenged her Labour opponents to table a motion of no confidence in her Government. Jeremy Corbyn promptly did so.
• Addressing MPs, the Prime Minister added “… tonight’s vote tells us nothing about what it (the House of Commons) does support. Nothing about how – or even if – it intends to honour the British people took, in a referendum Parliament decided to hold … every day that passes without this issue being resolved means more uncertainty, more bitterness and more rancour. The Government has heard what this House has said tonight, but I ask members on all sides of the House to listen to the British people, who want this issue settled and to work with the Government to do just that.”

What happens Next?

• The Government will face a confidence vote tomorrow evening. Both the DUP and Brexiteer Conservative rebels have indicated that they would back the Government in the confidence vote. This means that the Prime Minister will almost certainly survive to fight another day.
• The Prime Minister confirmed that if her Government survives the no confidence motion, she will hold cross party talks with the DUP and senior MPs from across the House on next steps. Further discussion with the EU will almost certainly follow at the weekend.
• The Government now has three Parliamentary days in which to make a statement and lay down a motion formally explaining what it plans to do next. This means that we will see the Government’s Brexit Plan B motion and statement from the Prime Minister by Monday 21st January.
• Members of Parliament who either want to force a second referendum or who would like to see the UK seek a softer Norway style Brexit by joining the European Economic Area (EEA), will see the Brexit Plan B motion as their moment of greatest leverage. Expect to see a series of amendments tabled next week as MPs seek to fully take control of the Brexit process.
• However, the PM seems intent on holding the line, saying only that she will seek “genuinely negotiable” alterations to her existing deal. It’s not at all clear what “genuinely negotiable” yet means.
• This whole process increases the chances of an Emergency EU Council Summit being convened in the coming weeks. Sign off for any of the changes to the Withdrawal Agreement or Political Declaration necessary to agree a Plan B Brexit would, at this point, require sign off from EU heads of Government. Similarly, if the UK were to hold a second referendum, an extension of Article 50 would be needed, something which would require the unilateral consent of EU leaders at a special Summit.

Why does this Matter?

• The historic proportions of her defeat tonight cannot be over-estimated, but in calling Mr Corbyn’s bluff Mrs May has wrestled back some of the initiative. The Prime Minister is nothing if not resilient and she intends to battle on and attempt to get a Brexit deal through Parliament. Her party will, in a bizarre reversal, rally behind her on the confidence vote tomorrow, having hammered her Brexit deal this evening.
• With the PM almost certain to survive tomorrow’s no confidence vote, Labour’s repeated calls for an immediate General Election are likely dead in the water. By calling a no confidence vote before it could be won, Jeremy Corbyn may just have shot himself in the foot. While the PM’s Party will quickly unite around her, internal Labour pressure on Jeremy Corbyn to back a second referendum will grow. Corbyn has made it clear that he does not favour that second referendum, however, Labour remainers secured a policy shift at Party Conference last year. That means Labour must move towards backing a second referendum if forcing an early General Election is no longer a possibility.
• To avoid a no deal Brexit the PM now has to test whether what has “sufficient support” in Westminster is “genuinely negotiable” in Brussels. The EU have made clear they have no intention of reopening negotiations, particularly in respect of the backstop, underscoring how irreconcilable the two sides still appear to be.  
• Why does this matter? Because, unless there is a material change and Parliament is able to reach some kind of consensus and sign a deal with the EU, the United Kingdom is still set to leave without a deal at 23:00 GMT on the 29th March.

And finally, ... a no confidence motion - the facts

• A no confidence motion is a means of testing if the Government has the confidence of the House of Commons, and it is the only way in which Opposition MPs can force an early General Election (the other way being if the Government get the backing of two thirds of MPs for an early election).
• If a no confidence motion is tabled by the Leader of the Opposition the Government are obliged to allow debate and a vote on that motion.
• If the Government lose that vote, then Opposition parties are given 14 calendar days in which try and form a new Government that can command the support of a majority of MPs. If no such new Government can be formed, then there must be a General Election.
• If the Government win a confidence motion then they continue in office as before. However, there is nothing to stop the Opposition tabling another no confidence motion, but the Government are only obliged to allow a vote on that motion if there has been a material change in circumstances that suggests the result may be different to the first confidence motion vote.