Boris Johnson could become the first Prime Minister ever to be interviewed under police caution amid growing pressure for him to release the potentially explosive inquiry into Partygate within hours.
Sue Gray has identified eight parties that may have broken lockdown rules, reports The Telegraph, and could publish the findings as soon as tomorrow - possibly after Prime Minister's Questions.
The civil service inquisitor is said to expect Mr Johnson to release her findings in the full form they are provided to him within hours of receiving them.
She has also obtained pictures of the parties, showing the Prime Minister and others close together next to wine bottles, reported Sky News on Tuesday.
A day of high drama and chaos in Westminster started when Scotland Yard chief Dame Cressida Dick announced this morning that the Metropolitan Police will finally probe alleged lockdown breaches in Downing Street and Whitehall.
The decision, announced at a London Assembly committee, could lead to Mr Johnson becoming the first serving prime minister in over 15 years to be interviewed by police - after Tony Blair was quizzed over the cash for honours scandal in 2006.
At the time, Blair reportedly made it apparent that he would have to step down if he was interviewed under caution.
Policing sources told The Times that Mr Johnson having to speak to detectives during the investigation 'appears inevitable'.
The probe represents a step change in the seriousness of the situation facing the Prime Minister and senior staff at No10, who could face £100 fines, and, more seriously, the end of their political careers.
Events had descended into farce by lunchtime today as No 10 insisted that the criminal probe meant that parts of an internal report by Ms Gray would not be published until it was completed.
This stance, seemingly kicking the most potentially damaging parts of the report into the long grass, was swiftly abandoned, however, after Scotland Yard said full publication would not affect its inquiries, which carry fines as the most serious punishments.
Government sources insisted the final decision will be taken by Ms Gray after discussions with lawyers, and there is no 'pressure' from Downing Street. Sources tonight suggested that she could now release the full report as soon as Wednesday.
That would force the Prime Minister to come to the Commons this week and could intensify efforts by Tory backbenchers to oust him from office.
Conservative Andrew Bridgen said he hoped Ms Gray's report into allegations of Downing Street lockdown parties would be published on Wednesday.
The MP for North West Leicestershire told Channel 4 News the conclusions of the civil servant's inquiry should be published 'unredacted'.
Mr Johnson also faced claims that he kept news of the police probe from senior ministers when Cabinet met this morning, leaving them to find out from the media when they turned on their mobile phones as they left No10.
The Prime Minister's spokesman said he was aware of 'speculation' that the Met did not object to the publication of the report.
He said: 'The advice that I have had is that there are still ongoing discussions, there are still details that need to be worked through between both the police and the investigations team.
The spokesman said decisions on publication were a matter for the Cabinet Office and police and 'we are not, as in No 10, seeking to block that in any way'.
He added it 'certainly remains the case that we would want it to be published as soon as possible' although 'I would not want to be perceived as putting undue pressure on either the investigations team or the police'.
It added up to yet another day of crisis and drama surrounding Mr Johnson, who faces the prospect of becoming the first PM to be grilled by police as a potential lawbreaker within living memory.
Addressing MPs today In the Commons, he said he welcomed the police move, saying it could give the public 'clarity' and 'draw a line' under the allegations.
In a brief reference before making a statement on Ukraine, he insisted the government would remain '100 per cent focused on dealing with the people's priorities'.
The PM's spokesman insisted he will 'cooperate fully' if required to be interviewed.
It is not clear whether Mr Johnson was personally involved in any of the the incidents under criminal investigation. The offences carry £100 fixed penalty fines.
But there is no precedent in modern times for a sitting PM to be subject to a criminal probe, let alone convicted. Tony Blair was interviewed as a witness during the cash-for-honours affair, but not under caution.
The chaos erupted on Tuesday after it was revealed that a birthday party, complete with cake and singing, was held for Mr Johnson in No10 in June 2020.
Boris Johnson came out fighting in the Commons today after police dramatically launched an investigation into Partygate
Scotland Yard chief Dame Cressida Dick announced that the force has now launched a probe into lockdown breaches in Downing Street and Whitehall over the past two years
Downing Street has conceded staff 'gathered briefly' in the Cabinet Room following a meeting after it was alleged 30 people attended and shared cake despite social mixing indoors being banned.
Cabinet was meeting as the new dropped from the Met, with Jacob Rees-Mogg and Liz Truss among those attending
Before the latest revelations there were signs that the Tories might be clawing back some ground on Labour after months of slumping support
Former Cabinet minister David Davis, who called for Mr Johnson to quit last week, said today that the 'nightmare gets even worse'
Mr Bridgen said: 'I think the sooner the report comes out now the better, if it is completed, because we can't sit under this cloud, paralysing the Prime Minister, paralysing the Government.'
Referencing the threat of Russian invasion into Ukraine, he continued: 'These issues that are hanging over our Government at the moment, they need to be dealt with as soon as possible and I do hope that Sue Gray gets her report in tonight and it is published tomorrow.'
Told that Conor Burns, a minister and ally of the Prime Minister, had said Boris Johnson had been 'ambushed with a cake' during the latest allegation of a birthday party in June 2020, Mr Bridgen replied: 'You can spin it how you want to.
'This isn't about cakes, this isn't about parties, this is about misleading Parliament and whether we can trust the word of the Prime Minister.'
The news broke during Cabinet this morning, and Mr Johnson informed ministers of the development at the end - but there was no discussion, prompting rumours of irritation.
Despite a mounting Tory revolt, a slew of MPs gave noisy support to the premier in the chamber, branding the accusations 'vexatious' and asking why Keir Starmer was not under investigation.
During a hearing at the London Assembly, Dame Cressida pointed out that under guidelines police have not examined historical allegations of lockdown breaches unless there is clear evidence and a lack of a defence.
'We have a long-established and effective working relationship with the Cabinet Office, who have an investigative capability,' she said.
'As you well know they have been carrying out an investigation over the last few weeks.
'What I can tell you this morning is that as a result of the information provided by the Cabinet Office inquiry team and, secondly, my officers' own assessment, I can confirm that the Met is now investigating a number of events that took place at Downing Street and Whitehall in the last two years in relation to potential breaches of Covid-19 regulations.'
Deputy Assistant Commissioner Jane Connors, the Metropolitan Police's lead for Covid-19 who was previously embroiled in row over policing of the Sarah Everard vigil, has been put in charge of the investigation.
A Scotland Yard spokeswoman said: 'The Special Enquiry Team will lead the investigations. DAC Jane Connors will oversee the investigation in her role as the Met's lead officer for Covid.'
Jacob Rees-Mogg walked out of Cabinet and straight over to cameras to vow loyalty to Mr Johnson.
'I am honoured to be under his leadership,' the Commons Leader said.
But former minister David Davis - who last week called for Mr Johnson to quit - said: 'With the police now investigating, this nightmare gets even worse. We have to be able to get back to dealing with real threats as quickly as possible.'
Transport Secretary Grant Shapps admitted this morning that he was 'upset' by the latest allegations that up to 30 people gathered in the Cabinet Room, presented Mr Johnson with a cake and sang to him.
Sent out to field questions, Mr Shapps was pushed on why interior designer Lulu Lytle, who had been refurbishing Mr Johnson's flat, had come down three flights of stairs and was present at the alleged party.
'You are asking me questions I can't provide the answer to because I wasn't there,' Mr Shapps said.
Mr Shapps - usually one of the most loyal ministers who has been a key figure trying to quell the revolt up to now - told Sky News: 'It was his (Boris Johnson's) birthday and these are people that he worked with all the time.
'As I said, I don't seek to defend it. This is for Sue Gray to decide on whether this was appropriate, she'll make the recommendations.
The minister seemed to lay the blame squarely on Mr Johnson's wife Carrie - sometimes dubbed Carrie Antoinette by critics due to her influence behind the scenes - who is believed to have organised the gathering in the Cabinet Room on June 19, 2020.
'Look, as the Prime Minister's said, where mistakes were made, even though it wasn't… I mean, he would have turned up and the cake would have been there,' he told ITV's Good Morning Britain.
'He didn't know about it, and it clearly shouldn't happen.
'But Sue Gray will get to the bottom of that; the Prime Minister's already said there will be consequences falling out from the Sue Gray report, and my hope is we can get to see that very quickly.'
He added: 'We know that this was a surprise, the Prime Minister obviously wasn't involved in that surprise, but we need to have a full understanding of all of that.'
Tory MPs are on high alert for more damaging revelations after it emerged that the PM's 56th birthday celebration included a Union Jack cake, Marks and Spencer's nibbles and singing.
The event, first revealed by ITV, was apparently already on Ms Gray's radar. Earlier that day Mr Johnson had posed with his arms outstretched with children at a school in Hertfordshire to show the importance of social distancing.
In March, Mr Johnson had praised a girl named Josephine who wrote to him saying she was cancelling her seventh birthday while the pandemic was raging.
Getting to his feet in the Commons this afternoon, Mr Johnson said: 'A few weeks ago I commissioned an independent inquiry into a series of events in Downing Street and the Cabinet Office as well as some other Whitehall departments that may have constituted potential breaches of the Covid regulations.
'That process has quite properly involved sharing information continuously with the Metropolitan Police.
'So I welcome the Met's decision to conduct its own investigation because I believe this will help to give the public the clarity it needs and help to draw a line under matters.
'But I want to reassure the House, Mr Speaker, and the country that I and the whole Government are focused 100 per cent on dealing with the people's priorities, including the UK's leading role in protecting freedom around the world.'
Dame Cressida told London Assembly members that investigations were carried out for 'the most serious and flagrant type of breach' where there was evidence and three criteria were met.
'My three factors were and are: there was evidence that those involved knew, or ought to have known that what they were doing was an offence.
'Where not investigating would significantly undermine the legitimacy of the law.
'And where there was little ambiguity around the absence of any reasonable defence.
'So in those cases, where those criteria were met, the guidelines suggested that we should potentially investigate further and end up giving people tickets.'
A Cabinet Office spokesman said: 'The investigation being carried out by Sue Gray is continuing.
'There is ongoing contact with the Metropolitan Police Service.'
Dame Cressida said that the police officers on site at Downing Street concentrate on 'protective security'.
She said: 'There are a number of officers posted in the surrounds of Downing Street and indeed what we call generally the government security zone.
'They have a very clear role and that is protective security. You'll be aware that the ones you see are all armed, and they have a job to do.
'In relation to anything they may have seen or heard, or done or not done. Again, I'm afraid I'm not prepared to comment.
'But I can assure you that we are carrying out our investigations and if that is a relevant matter, we will find out about that.'
Told that there must by CCTV of the alleged breaches in Downing Street, Dame Cressida said: 'I don't anticipate any difficulty in obtaining the evidence that it is both necessary, proportionate and appropriate for us to obtain in order to get to the right conclusions.'
The Met said it had carried out 'detailed assessments of these outline findings' from the Cabinet Office.
The force is investigating whether regulations were breached 'during events at Downing Street and Whitehall on a number of dates'.
'The MPS has written to the Cabinet Office this morning with a formal request for it to refer all relevant information gathered from its inquiry in relation to events on the dates in question to support the police investigations,' the statement said.
The PM's official spokesman said: 'Firstly, the Prime Minister thinks it is entirely right for the police to investigate these matters.
'He commissioned the Cabinet Office to establish the facts and, as set out in the published terms of reference, and as the (Met) Commissioner has said this morning, the independent process has always involved the sharing of information with the Met and the ability for the Met to take forward and investigate matters pertaining to the law, as is right.
'The PM fully acknowledges the public's anger and concern about what has been reported, he has taken responsibility for his judgments made and it is right the Met should be now given the time and space to undertake their investigations.
'It will provide the public with welcome clarity and help draw a line under these events and everyone required will fully co-operate in any way they are asked.'
No10 said Cabinet had not discussed the police investigation, although he mentioned it at the end of the session.
The spokesman said: 'That was confirmed by the police while Cabinet was taking place so he didn't reference it specifically, he alluded to that at the end of Cabinet but beyond that no.
'He made those comments about ensuring the Government is not deterred from getting on with the job, he didn't go into detail about the Met given that Cressida Dick made her comments while Cabinet was taking place.'
The spokesman added: 'The Prime Minister was made aware shortly before Cressida Dick announced that in her session.'
Asked if Mr Johnson knew about the investigation before Cabinet, the spokesman replied: 'Yes.'
Ms Gray will pause investigating or publishing any party allegations that the police are inspecting but is free to publish other matters in her inquiry, No 10 has suggested.
The PM's spokesman said: 'As the terms of reference make clear, they won't publish anything that relates to the work of the police, there are a number of events and allegations that they have looked into that the police said don't reach their threshold, which they are able to continue looking into.
'And it is my understanding that they will be able to publish detail about those events rather than ones which the police might be taking forward.'
He added: 'It's up to the investigation team when they publish, it's my understanding they are able to publish the aspects that aren't a matter for the police.'
Discussing the events the police are investigating, the spokesman said: 'I think under the terms of reference that work (for the Gray inquiry) pauses, I don't know what that means once the Met Police's investigation concludes, whether they return to them and continue.'
The terms of reference for the Gray inquiry state: 'As with all internal investigations, if during the course of the work any evidence emerges of behaviour that is potentially a criminal offence, the matter will be referred to the police