Boris Johnson’s hopes of striking a new Brexit deal with the EU were dashed today after a furious early morning phone call with Angela Merkel.
The German Chancellor is believed to have told the Prime Minister the only way for a new agreement to be struck would be for the UK to agree to Northern Ireland remaining in the customs union.
Mr Johnson refused and just like that the path to an accord appeared to vanish while the chances of a No Deal split increased dramatically.
So what happens now? Below are all of the answers to all of the key questions as Britain braces for three weeks of Brexit chaos.
What happened today?
In simple terms the Brexit negotiations went up in flames. Ms Merkel reportedly told Mr Johnson the only way for the two sides to agree a deal would be if the PM agreed for Northern Ireland to stay in the EU’s customs union ‘forever’.
Such an approach would avoid the return of a hard border on the island of Ireland and would mean the Irish backstop could be scrapped.
But it would also mean Northern Ireland effectively being separated from the rest of the UK.
Mr Johnson apparently told Ms Merkel that her position meant a deal was ‘essentially impossible, not just now but ever’.
Donald Tusk, the president of the European Council, then upped the stakes as he publicly criticised Mr Johnson.
Mr Tusk claimed the PM was trying to win ‘some stupid blame game’ as he accused him of not actually wanting a deal.
What does this mean for the Brexit talks?
It appears Mr Johnson’s ‘final offer’ on Brexit – which he only submitted to the EU last Wednesday – is now officially dead with the bloc of the view that the PM’s blueprint cannot act as the basis for a formal divorce agreement.
With just 23 days until the October 31 deadline that means the chances of a disorderly split from the bloc have gone up significantly.
Downing Street is not willing to compromise any further and the EU does not believe Mr Johnson’s ideas on how to delete the backstop are workable.
It is therefore hard, if not impossible, to see how the two sides could arrive at a deal within the next three weeks.
So what happens next?
Mr Johnson will prorogue Parliament this evening as he prepares to set out his new domestic legislative agenda in a Queen’s Speech next Monday.
Ending the Parliamentary session today means that the PM will not face difficult Brexit questions in the Commons for the rest of this week.
That will in theory allow him to focus all of his energies on Brexit. Brussels had suggested the end of this week would be the moment when the two sides would know whether an agreement could be struck before a crunch EU summit on October 17.
If there is no agreement by close of play on Friday then the bloc’s attentions will then switch to whether to offer the UK a Brexit delay.
However, given the acrimony today following the PM’s call with Ms Merkel, it looks likely that both sides already know that they will not agree a deal.
The effective collapse of the talks has prompted rumours that Mr Johnson could make a statement in Downing Street setting out his proposed next steps but nothing has been confirmed.
Why is this EU summit so important?
The scheduled European Council meeting in Brussels on October 17-18 is the last one due to take place before the Halloween Brexit deadline.
It had been earmarked as the last moment at which a deal could be agreed between Britain and the bloc.
But the chances of an accord being signed off at the summit now appear minuscule.
It is likely that instead of focusing on a deal the summit will now focus on whether a Brexit delay will be offered to the UK.
If a deal is off the table in the run up to the summit it is possible that Mr Johnson could choose to boycott the get together entirely.
If the PM’s deal is dead, does that mean there will be a No Deal Brexit?
It is hard to answer this question definitively for a number of reasons.
MPs have passed an anti-No Deal law – the so-called Benn Act – which will force the PM to ask Brussels to push back the Brexit date to January 31 next year if no agreement has been made by October 19.
Assuming the EU agrees to such an extension then a No Deal Brexit will be avoided.
But the PM and the government remains adamant that the UK will leave the bloc with or without a deal on October 31.
Number 10 has conceded that it will have to comply with the Benn Act and ask for a delay.
Boris Johnson and Angela Merkel, pictured in Berlin in September, today had a fiery phone call in which the German Chancellor reportedly told the PM Northern Ireland would need to stay in the EU customs union for a Brexit deal to be agreed
But Downing Street has also said it intends to make clear in public and private to the EU that the government does not actually want an extension in the hope that Brussels will refuse to offer one.
So it is possible that the government will ask the EU for a delay (as required by the law) while also telling the bloc not to grant one.
In those circumstances the UK’s Brexit fate will rest entirely in the hands of the EU. If the bloc was to rule out an extension then the UK would leave without an agreement on Halloween.
If the EU does offer an extension the PM will be legally obliged to accept it. It could get very messy indeed.
If the EU agrees to an extension will there then be a general election?
Yes, almost certainly. Opposition leaders including Jeremy Corbyn have said that they will agree to an early election if and when a No Deal Brexit has been ruled out.
If the EU offer a delay at the summit then MPs could vote the next week to trigger a snap poll.
There are two mechanisms for holding an early election. The first is for the PM to be defeated on a confidence motion, and two weeks to pass without another confidence vote being won.
The second – and more likely route – is to have two-thirds of the Commons vote for an early election. If that motion was passed on October 22, the campaign legally has to be at least 25 working days later.
Elections are traditionally held on a Thursday. That gives a potential date of November 28.
Could there still be a second referendum?
A general election looks more likely but there are plenty of MPs who want a second referendum instead.
Former Tory Sir Oliver Letwin has warned that an election would not be a satisfactory way of settling the Brexit debate, as it would be clouded by a host of other political issues.
Some senior Labour figures are also sympathetic to such concerns.
The route to a referendum would probably involve defeating Mr Johnson in a confidence vote, and then replacing him with a ‘unity’ candidate as PM such as Labour’s Margaret Beckett or ex-chancellor Ken Clarke. They would then push through the legislation for a referendum.
However, it looks like a very tricky proposition, with estimates that it could take up to six months to prepare a national ballot. There are also major questions about what the question would be, and whether No Deal would be on the ballot paper.
What happens if Boris Johnson wins a majority at the early election?
Downing Street has made clear that the PM is now planning to fight an election on a No Deal platform, as the EU will not compromise.
The pledge to make a ‘clean break’ is designed to absorb the votes that have flowed from the Tories, and indeed Labour in its northern heartlands, to the Brexit Party.
Jeremy Corbyn, the Labour leader pictured in London earlier this month, has said he will support an early general election if and when a No Deal Brexit has been ruled out
Victory could require a fundamental realignment of the country’s traditional political dividing lines, with the Conservatives needing seats like Bolsover – stronghold of hard-left veteran Dennis Skinner.
With a majority and a new mandate, Mr Johnson could then take the UK out of the EU without a deal – or have more leverage to extract concessions from Brussels.
What happens if Jeremy Corbyn wins a majority at the early election?
On current polling, Labour looks unlikely to secure a majority by itself. But the SNP has signalled it could prop him up, in return for permission to hold a new independence referendum.
Labour has vowed to renegotiate the existing Brexit deal and go into an election promising to hold a second Brexit referendum between a new divorce package and Remain.
What if there is another hung Parliament?
With the polls highly volatile, it looks quite possible that an election could deliver broadly similar numbers to the current Parliament.
This would be possibly the most disconcerting outcome for the country – sending politicians straight back to the drawing board to try and final a way to break the deadlock.