Boris Johnson's allies fear lockdown party revelations could be knockout blow for PM

It's the silence from his Conservative colleagues that's deafening.

It's the empty government green benches as the Paymaster General Michael Ellis is dragged out to defend the prime minister over Downing Street parties.

It's the quiet calculations MPs and would-be rivals are making about the precariousness of Boris Johnson's position and what might happen next - this is a prime minister in deep trouble.

Mr Johnson's colleagues have, in the main, gone to ground.

MPs eschewed the chamber and the offers of talking on camera about the latest revelations: that the prime minister's private office emailed Downing Street staff on 20 May 2020, when the country was in lockdown, to invite them to a drinks party in the garden with the instruction to 'bring your own booze'.

An eyewitness tells me the prime minister and his wife attended the party, when just earlier in the day the public was told from the Downing Street news conference podium to only meet one person outside in a public space.

For weeks, the prime minister has told the Commons and the cameras that not only were no rules broken in No 10, but he hadn't broken rules himself.

Now his party and the public are looking on asking how he possibly squares this circle?

Scottish Conservative leader Douglas Ross told Sky News on Tuesday it would be "utterly despicable" if this party had gone ahead.

He told the PM to stop hiding behind the inquiry by senior civil servant Sue Gray, and come clean about whether he attended it or not right now. He also repeated his view that the PM should resign if he's found to have misled parliament.

For many other colleagues, the mood is not much less forgiving, even if they are not going public.

One senior Conservative told me today that even those loyal to Mr Johnson are "in despair" over these allegations.

Another told me: "This is as bad as it gets. The fact [Oliver] Dowden [then culture secretary] was telling people [on 20 May] what they couldn't do from one room and less than an hour later this was happening in the Downing Street garden is indefensible."

The prime minister himself is trying to tough it out. I'm told by one source that at today's cabinet meeting, Mr Johnson was "full of forced purpose and mission" and "bulldozed over everybody".

But this strong man approach is coming from a position of acute weakness - for a politician who has an amazing ability to wriggle out of political headlocks, this time Mr Johnson looks caught in a vice-like grip.

"There's going to be an awful lot of heat around this," says one former cabinet minister.

Another government figure put it another way: "I don't think in the next 48 hours what happens next will crystallise. This just rumbles on.

"But over the next couple of weeks it's going to look like he's jammed into a corner. Maybe he'll roll the dice and front it out, but fundamentals are fundamentals and colleagues are increasingly beginning to ask when, not if."

Colleagues - and would-be successors - are now waiting on three things.

First, what will the PM himself do and say? Will he try to stonewall or will he come clean and apologise? MPs I have spoken to are clear they would prefer honesty from their leader - in part to placate the public but also as a signal he's listening to criticism, and trying to change his ways.

Second, what are the Metropolitan Police going to do? If the force decides to investigate the alleged party, then things get even more serious.

That the police are even considering the need to investigate a sitting prime minister and his team for allegedly breaking laws that they themselves set - and other people were punished by - is deeply uncomfortable territory. Tory MPs will have to ask whether this is an acceptable state of affairs.

And third, what does Sue Gray conclude? Much will rest on her assessment of the parties in Number 10 and beyond.

On whether Mr Johnson will face a leadership challenge in the coming months, MPs are divided or unsure as they await to see how these latest damaging revelations play out.

MPs will be anxiously watching their postbags and the polls, all with an eye on the next critical ballot box test for Boris Johnson in the local elections in May.

It has been a stunning fall from grace.

Mr Johnson was the undisputed champion in 2019. Now he is a bloodied prime minister seriously on the ropes with even his allies fearing a knockout blow.