"Planet Boris is the strangest place in the world - no rules apply," a cabinet minister told me a few days ago as they marvelled at the strangeness of the current political universe.

Events had been disastrous, they admitted, yet they seemed sure at that moment that the prime minister's ability to defy any normal political gravity would see him through.

But then, on Tuesday night, a video emerged showing aides joking about a Downing Street event last Christmas as Britain was in lockdown. The humiliating leak engulfed No 10 in a fresh crisis that shows no sign of easing.

So this weekend it is worth asking if "Planet Boris" might actually, finally implode?

One senior official summed up the state of play simply: "It's a disaster."

Day after day, for more than a month, Downing Street has been struggling to keep hold of events.

There have been miscalculations and missteps - attempts to change the rules to protect one of their own, Owen Paterson; the disastrous efforts to close down stories about Christmas parties last year, and most recently, a fine for the Conservative Party over the financing of Mr and Mrs Johnson's lavish renovation of the No 10 flat.

The mistakes have been all the worse because they were miscalculations of Downing Street's own making. Almost nothing riles MPs and ministers outside the clique at the top of government more than No 10 making mistakes for which they all have to answer.

Each incident fuelled the opposition's main argument they had been making for months - that Mr Johnson behaves as if he's exempt from following the rules.

Whether it's the Christmas parties or the cash for the flat, the mess has highlighted this prime minister's complicated relationship with the truth, which we've discussed here before.

There has been little sense that No 10 has been able to, you might say, take back control. In fact, as pressure has cranked up in recent days it's been hard sometimes to get any sense of what is going on at all.

The atmosphere inside is described as deadly silent, horrible, as if the lights are on, but no-one's really home.

Some ministers loyal to Boris Johnson reject the notion that anything is serious or somehow in permanent decline.

It's true that the prime minister's career has been built on proudly dismissing, and dismantling norms. It's also true that he has slipped before, but surged back, time and again. He is the campaigner of his generation, they believe, and can recover.

But it is notable that MPs who were involved in getting Boris Johnson to No 10 say privately, and increasingly colourfully, that he has to sharpen up.

One of them told me that Downing Street has become "like a theme park of soft decision-making and avoidance".

"There's the helter-skelter, there's the lost-in-space ride, there's the final ride which is the 'make a decision and see if you can stick to it by the end of the ride'."

With deep irritation they told me: "They all have to be shut down. We do not need a fairground. Downing Street has to be run like a military camp."

Others talk of drift and decline. "Nothing important's discussed in our meetings," one says.

At the start of meetings the PM verbally encourages them to contribute, but the implicit message is, "Don't speak up." they feel. Ministers sometimes choose to stay silent. One jokes that they message each other instead about how bad things are.

After the last few torrid weeks, the trouble, according to one former cabinet minister is that the different Tory tribes, who sometimes can't stand each other, now find themselves able to agree. The problem for Mr Johnson is that the only thing they agree on is how unhappy they are.

According to this analysis, moderates who might see themselves as "internationalists" are grumpy about foreign policy and the government's cuts to foreign aid. The Brexiteer gang are cross that he's not being tough enough about Northern Ireland.

The "red wall" group, with new seats from 2019, know they owe them in large part to Mr Johnson, but they also see themselves as champions of their areas. And some of them don't feel they have much to show for that just yet. Some Northern Tories are said, increasingly, to believe that the PM is "all mouth, no trousers".

And among the right-wing of the party, there's increasing frustration that the government won't take more radical action - changing human rights law, for example - at the Channel to stop migrants crossing in small boats.

These groups shift around of course, but right now they are said to be "coagulating" - instead of spats between each other they are coming together on one thing, that the recent mess can't be allowed to go on.

Many MPs are hopeful it could end up with a new Downing Street operation. One said there needs to be a "clear-out of the 'born to rule' cabal", suggesting that the recent fiascos were inevitable given who has been around the PM.

"Frankly none of us should have been surprised when the grown-ups leave, that the children have an illegal house party," the MP said, adding that the Downing Street party fiasco should be the moment to "clear the sycophants out".

There isn't much sign yet that Mr Johnson is planning a big shake up of his team though. Allegra Stratton, who resigned on Wednesday as a senior government spokeswoman, carried the can for this week's humiliating leaked video footage.

And there's chatter that the prime minister has made a strategic decision to hold on to director of communications Jack Doyle for now, while lining him up to take the fall when the inquiry emerges.

Two sources have told the BBC Mr Doyle's resignation was offered but refused, although No 10 has denied this happened.

But as so often, while the Westminster rumour mill loves almost nothing more than speculating about who is in and who is out, the fairly desperate state of affairs is in the end, always, about the boss. Tone and culture is set by the person at the top, whoever else is up or down.

That's why what's next is, first and foremost, down to the decisions Mr Johnson makes himself. Does he acknowledge there have been problems? Will he resolve to lead in a different way? Will he "[look] in the mirror", as his friend and former minister Robert Buckland urged him publicly to do, and say "surely I can do this better"?

If not, well, Mr Johnson still has his huge majority. He still has enormous powers as the leader of the government, and as the political campaigner and celebrity.

Yet this week it feels sentiment has moved in the Tory party, with more and more of his own side imagining what life might be like under a different leader.

Is the moment nearly upon them when he becomes less a flawed, but fundamentally sparkling, asset, than a liability?

A former minister who has analysed the party tribes even suggests "stage one" of a leadership change is complete: when the party agrees among itself privately that the PM is running out of road.

"Stage two", however, is the who next, how and when, and "that can take a very long time".

Right now, it seems far-fetched to imagine any kind of challenge soon. Don't doubt, however, that allies of potential candidates for next time round, Chancellor Rishi Sunak and Foreign Secretary Liz Truss, are thinking hard about what's next.

There are even whispers that some MPs have been urging former cabinet minister Jeremy Hunt to put himself forward soon as a kind of safety, continuity candidate in the new year, even though right now, I'm told, "He doesn't want to play."

Of course, anyone that's mentioned in connection with the leadership would publicly deny any ambition, or any plotting. Breathless conversations about replacing leaders are rarely far from the topic of conversation in Westminster.

A former minister admits they have been approached about exactly that twice in a matter of days, but cautions that to act any time soon would be "collective political suicide". With the pandemic still raging, the economy pretty fragile, and only two years on from the last election, would the public really want to indulge the Tory party tearing itself apart in public, yet again?

But the volume of discussions about replacements for the prime minister is increasing. Many MPs believe it's down to him to get a grip if that's to fade.

Mr Johnson faces two tests next week, that could deepen the sense of an impending Christmas crisis, or dial down the drama. There's a potentially huge rebellion in the Commons on Tuesday about the Covid regulations. Dozens of his backbenchers have already gone on the record to say they will vote against the plans.

With Labour support, the vote will pass, but a huge Tory vote against would display a real two fingers up to No 10. The whips and Mr Johnson, equally, have a huge opportunity to try to quell the anger in the next few days.

And there's the possibility of a different kind of rebellion next Thursday, when the by-election takes place to replace Owen Paterson as MP for North Shropshire. Many Conservatives fear doom on the ground there. A terrible result in what should be a safe seat would heighten the danger for the PM.

As we head into the last week of Parliament in 2021, there is plenty of peril. The prime minister faces risks all around.

It's madness to write him off - his biography is a living warning against that. Yet, a backer of the prime minister told me that while the situation doesn't have to be terminal, it has - they said with no pleasure - to change.

"If it doesn't, we all know where it leads. It leads to the front door."