So what might happen next?

HOLD THE VOTE LATER With more than 100 Tory MPs suggesting they will vote against the deal, together with Labour, the Lib Dems and the SNP, a defeat tomorrow night seems most likely.

If Theresa May survives the aftermath and doesn’t quit – or if she delays the vote – she could go to Brussels this week to seek a better deal. This may involve a clear concession of a time limit on the backstop, or a unilateral exit mechanism for the UK.

A new Commons vote on the deal would then take place before Christmas. If the PM wins, Brexit goes through. TORY REBELLION With Europe unlikely to provide the concessions Mrs May asks for, Tory backbenchers could decide to try to get rid of their leader. If a 48-letter threshold is reached, a no-confidence vote among Tory MPs would follow.

Mrs May could win this but if she does not challengers such as Boris Johnson would be able to enter the leadership fray. A more Brexit-friendly leader could go on to try to negotiate a looser Canada-style deal, which would involve more problems with the Irish backstop. NO-CONFIDENCE VOTE AND ELECTION Labour could table a motion of no confidence in the Government. This could even happen if the deal passes because the DUP – which props Mrs May up – has said it will not support the current agreement.

If the Tories lose a vote of no confidence – and if Labour is then unable to form a minority administration – a snap election would be held. This would raise the prospect of Jeremy Corbyn taking the keys to No.10 and attempting to negotiate his own Brexit deal. THE NORWAY OPTION If Mrs May’s plan is voted down, Parliament would start to assert control.

An MP could put down an amendment calling on Britain to join the European Economic Area, which allows non-EU members access to the single market. However, Labour has spoken out against such a deal, and Tory Brexiteers would oppose it because it means continued freedom of movement. SECOND REFERENDUM A Remain-supporting MP could put down an amendment calling for a second referendum on Mrs May’s deal. Such an outcome would require Brussels to agree to an extension to Article 50, meaning Brexit Day would be deferred.

This would require a Commons vote – but both parties promised to respect the 2016 referendum result in their manifestos last year. If a second vote is held, this could lead to Britain staying in the EU. NO DEAL If Mrs May’s deal is defeated, and the EU does not offer any more concessions, then Britain could crash out without a deal. This would mean we would trade with our neighbours on WTO terms, with the possibility of medicine shortages and gridlock at ports.