Coming less than 10 minutes apart, it was hard not to be left with the impression that their exits are connected - though sources close to both men insist this was not a coordinated decision.

You can make of that what you will, but whatever the conversations behind the scenes, there is one thing that cannot be disputed: they have just made life incredibly difficult for the prime minister.

Politics Hub: 'It's all over' - PM fighting for political life

You could see how difficult things were earlier in the day when Downing Street allowed TV cameras into the cabinet meeting.

The mood in there was dire. You could read it on ministers' faces - gone the buoyant words about taking back control and seizing the day. It looked funereal in the cabinet room.

And that was before these dramatic walkouts. What do we have now? A situation where the conversation that was being held - slightly - below the surface, about who replaces Boris Johnson, is blown wide open now. This is now a battle, with charges coming not just from his backbenches, but running right up to his cabinet.

The PM has lost three cabinet ministers in the past couple of weeks. This is a very split cabinet now - and there will be only further questions within the party if Mr Johnson tries to carry on, which every single thing he has said up to this point suggests he will attempt.

Given all he has been through, had he been from any other generation, he might have resigned.

He's a prime minister who has never been afraid of rewriting conventions - but if a prime minister loses the support and the confidence of their chancellor and other senior cabinet ministers - that is a message to the prime minister; it's time to fall on your sword, that you no longer command that authority within your cabinet or in your party.

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Is he now in office, but not in power?

Right after Theresa May's dismal 2017 election, it was George Osborne who summed up the rest of her tenure when he labelled her a "dead woman walking" - she remained in office but had lost authority and power.

And ever since the partygate scandal, this is the question that has loomed over Boris Johnson.

He wants to carry on, but the authority in the party has been in freefall. The cabinet up to this moment had been outwardly, largely, pretty loyal.

These resignations are about the PM - the leader, the character

Oliver Dowden threatened to shake that two weeks ago when he walked out after those dire by-election defeats.

But no one followed him out, and Downing St managed to explain that away as the natural consequence of a co-chair taking responsibility for those heavy losses.

But there is no explaining away these two resignations. They are quite clearly about Boris Johnson - the leader, the character.

This is about integrity and not wanting to be tarnished by his leadership.

And immediately, for Boris Johnson and a restless Tory Party, it puts two people on the backbenches that now want him gone that can organise and mobilise MPs.

It is really now open war for Conservatives and raises open questions on whether, if Mr Johnson won't go, backbenchers will take matters into their hands, change party rules and force him out in a confidence vote.

Things are already unpleasant and could become really ugly in the coming days.

The public are ready to hear the truth: read Rishi Sunak and Sajid Javid's resignation letters in full

What does it mean for the opposition parties? Clearly, given the by-elections we've seen recently, the cynical view is that they'd rather fight Boris Johnson as leader in a general election.

And while Keir Starmer might tonight be saying that he should go for the good of the country, we have seen just this week Labour talking confidently about Brexit - trying to make inroads at the PM's moment of acute fragility.

The next few days could make clear whether we are heading towards the election that they are now demanding.