Can Boris Johnson now see how to win Brexit after Commons defeat? Robert Peston explains

Here are the important points about Saturday's emergency vote on Boris Johnson's Brexit deal - which turned into a vote on whether the prime minister should write to the EU requesting a three-month Brexit delay.

First, Johnson would have won if Northern Ireland's 10 DUP, his supposed partners in government, had not voted against him.

Johnson has paid a price for agreeing a Brexit settlement for Northern Ireland which the DUP sees as betraying the union of Northern Ireland and Great Britain.

Second, the narrowness of the defeat for Johnson implies that there is a route for him to secure Brexit by October 31 or shortly after that - because he needs just nine MPs to change their votes to take him across the line.

And there are six former Tory MPs who would back him at the last, and maybe three or four Labour MPs.

Third, it is damaging to the integrity of the UK that Johnson's Brexit will be delivered, if it ever is, in the teeth of opposition from the largest parties in Scotland and Northern Ireland, namely the SNP and the DUP respectively.

Boris Johnson's partners in government, the DUP - lead by Arlene Foster and her deputy Nigel Dodds - did not back in him the Commons. Credit: PA

Fourth, Johnson has said, in the Commons, that he will "not negotiate a delay to Brexit", even though the Benn Act obliges him tonight to send a letter requesting a three-month Brexit delay.

We should know next week, in a judgement from Scotland's Court of Session, whether the PM would be acting lawfully if he sends the letter asking for Brexit to be postponed but then immediately sends a subsequent message that he does not really mean it.

Fifth, Speaker John Bercow said that if Johnson did not request a Brexit delay, and if the courts ruled that the speaker should fill the PM's boots and request that delay on behalf of the UK, then Bercow would do so.

Sixth, next week may well be the last time supporters of a Brexit referendum will have a chance to secure a referendum, by amending the PM's Brexit legislation, the Withdrawal Agreement Bill.

Seventh, on Saturday's result, there would not be a majority for a referendum - and the crowd outside Parliament calling for a People's Vote may be seriously disappointed.

Eighth, if the government has its way, there will be another meaningful vote to approve Brexit, just like the one that didn't take place today, on Monday.

But Speaker Bercow has signalled he doesn't think the government would be following the unwritten rules if it asked MPs to undo what they've done so soon.

Ninth, more likely, given what Speaker Bercow has said, the important test of whether Johnson gets his Brexit will be the second reading vote on the legislation needed to deliver Brexit, the Withdrawal Agreement Bill, on Tuesday.

Speaker John Bercow has said he would sign an extension request letter. Credit: House of Commons

Tenth, if Johnson wins his vote on Tuesday, that means Johnson will probably get his Brexit, on or shortly after October 31.

Eleventh, if Johnson doesn't win the vote on Tuesday, at that point the EU will have to seriously consider any request from the UK for a Brexit delay.

EU leaders will probably ignore the delay request till then.

Twelfth, and this is your lot, at that juncture the EU will link any postponement of Brexit to the UK holding either a referendum or a general election.

So if there is still Brexit stalemate on Tuesday, MPs would then have just the 9 days before October 31 to decide whether to hold a general election, or settle Brexit in a referendum.

If they cannot make up their minds in those nine days, a no-deal Brexit on October 31 is a real and palpable risk.