When did Boris Johnson finally decide to quit?

On Thursday Downing Street shared pictures of Boris Johnson sharing a behind-closed-doors moment with his family and loyal ministers after giving a speech confirming he was stepping down as prime minister.

The mood of the photos looked happy if not a little sombre - but this is a stark change from the reportedly bitter and angry Johnson the night before.

In his resignation speech, he appeared to show his resentment at being abandoned by his party accusing Westminster of "herd instincts" despite only being slightly behind in the polls.

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On Friday morning, it appeared that he was fighting on till the very end to maintain his premiership - even if those around him knew he was doomed - and that the final blow was delivered when his newly appointed chancellor, Nadhim Zahawi, called on him to quit at 9am that day.

However, reports have since emerged painting varying accounts of the PM's final hours before he finally relented.

It is clear that that Johnson made a phone call to Sir Graham Brady (chair of the backbench 1922 committee) at 8.30am and told him he had decided to quit.

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But exactly when Johnson decided himself he had to go is disputed.

Johnson's former employer, The Daily Telegraph, said he had decided to resign by 6am on Thursday morning despite rejecting the idea during late-night meetings with his cabinet the day before.

Reporting sources close to Johnson, the Telegraph said the PM experienced a "moment of clarity" after his resistance the night before.

A source told them: "He is a fighter – his instinct was to have one last go at it, which he did,” said one ally who has been at Mr Johnson’s side throughout the last 48 hours and talked to him first thing.

"It didn’t work. He woke up this morning and realised the game was up."

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The Telegraph speculated the early morning resignations coming in on Thursday and pressure from Zahawi could have changed his mood.

They also noted Johnson had his regularly scheduled call with The Queen on Wednesday, although what is said between the two is kept a close secret.

One of Johnson's team said of the PM on Thursday morning "I would describe his mood as sanguine," adding: "He’s good-natured, good-humoured. There is a sadness, there is a mild frustration that it’s come to this. He is very self-aware."

The Daily Mail reports a similar timeline of events but says the mood was very different from the calm and sombre version presented by the Telegraph.

They said the PM was furious he had been forced out with his loyalists, white with rage at the plotters who had brought him down.

He reportedly resisted resigning throughout all of Wednesday evening telling those close to him: "If you are going to die, go down fighting."

The Mail said Johnson was moved by Home Secretary Priti Patel, one of his most ardent loyalists, telling him the game was up on Wednesday.

Despite this, he was reportedly still confident he could salvage the situation at 9pm on Wednesday pacing around No10 telling himself "we can do this!" And at one point declaring to an ally: 'It's not over. Is it over? Let's get it done."

He was still telling people at 11pm when he went to his private flat that he would fight on.

The Mail said they believe Johnson was sending texts at 5.30am and they suggested this was when doubts began to set in.

A source told the Mail: "He was pumped up the night before: Raging about the ministerial resignations, about the people who let him down," adding: "But sometimes, when you wake up, you see things differently."

They said by 6.30am he was writing his resignation speech.

The Times presents a slightly different version of events saying his team were completely frazzled by the end of Wednesday, with most telling Johnson it was time for him to go.

They suggest he made up his mind as he went to bed and was already working on his resignation speech by 6 am.

While sharing bacon sandwiches with his colleagues around 7.30am he told them "the game is up."

Regardless of how it unfolded, Johnson is still not out of office just yet and has made it clear that he plans to remain as prime minister until a new leader of the Conservative Party is in place, which may not be until October.

Whether or not he is allowed to do so remains to be seen.