THE threat of a serious challenge to Theresa May’s leadership is already lifting just hours after Boris Johnson became the second Cabinet minister to resign, warning “the Brexit dream is dying”.

In a day of high drama at Westminster, the Prime Minister rode out the resignations of the Foreign Secretary and David Davis, the Brexit Secretary, who, initially, appeared to have signed up to her softer Brexit at Friday’s Chequers summit.

Last night, Mrs May promoted the pro-Remain UK Health Secretary Jeremy Hunt to the post of Foreign Secretary, having earlier in the day promoted the pro-Brexit Housing Minister Dominic Raab to replace Mr Davis at the Department for Exiting the EU.

Matt Hancock was later moved from the Culture brief to become Mr Hunt’s replacement as Health Secretary while Jeremy Wright, the Attorney General, takes over at Culture.

Despite rumours of MPs gathering the 48 votes necessary to trigger a leadership challenge, Mrs May rallied Tory colleagues to her cause at a packed meeting of the party's backbench 1922 Committee in the Commons, where, amid cheers and the banging of desks, she called for unity and warned a Conservative mutiny would lead to a Corbyn Government.

HeraldScotland:

Tuesday's cartoon from Steven Camey

One Cabinet minister insisted the PM had put in a bravura performance and there was a “strong coming together” of MPs behind her.

He said: “The argument that really cut through for me and for lots of people was: unless we pull together we end up with Jeremy Corbyn as Prime Minister and nobody wants to see that.”

Robert Buckland, the Solicitor General, claimed the prospect of a confidence vote and challenge to Mrs May was “dead”.

He argued the resignation of two key Brexiteers from her Cabinet had actually helped her. “She is strengthened by all of this. Her most striking remark was to ‘lead is to decide.’”

Mr Buckland added: “That’s a good an end to the day as you could have possibly imagined.”

One minister described the idea of there being 48 signatures for a leadership challenge as “b******s”.

A call for unity was also made by Ruth Davidson, the Scottish Conservative leader, who has backed the Chequers plan as a “sensible compromise”. She urged colleagues to put their “shoulders to the wheel” and support Mrs May through the Brexit negotiations.

Her colleague David Mundell, the Scottish Secretary, argued the compromise deal would “bring significant benefits to Scotland and the whole of the UK and I urge everyone to get behind them”.

Meanwhile, ardent Brexiteer Jacob Rees-Mogg made clear he could not back Mrs May’s “quasi-Remain” Chequers Plan but, when asked about a challenge to the PM, replied: “No, I don’t think there will be a confidence vote.”

He said one issue of “grave concern” was how No 10 was briefing Labour MPs on Mrs May’s compromise.

“If the Government plans to get the Chequers deal through on the back of Labour Party votes, that would be the most divisive thing it could do and it would be a split coming from the top not from the members of the Conservative Party across the country,” said the Somerset MP.

After Mr Davis dramatically resigned just before midnight on Sunday, describing the Chequers Plan as a “dangerous strategy” and that under it "we are giving too much away too easily," his junior minister at the Brexit Department, Steve Baker, a fellow Brexiteer, followed suit.

All eyes were then on Mr Johnson, who had crudely described Mrs May’s compromise as “a big turd”.

He was due to host a lunch of foreign ministers at the Western Balkans summit in London but failed to turn up. Speculation spread through Westminster like wildfire as suggestions were made that he was closeted with advisers.

It later emerged he had telephoned the PM to tell her he was resigning; the seventh Cabinet resignation since Mrs May entered Downing Street.

He complained that her Brexit plan would leave the UK an EU "colony" and in a scathing resignation letter said, under Mrs May’s leadership, the UK was "heading for a semi-Brexit" with the dream of an outward-looking global Britain "dying, suffocated by needless self-doubt".

His resignation came just minutes before the PM stood up before MPs, telling them how her Chequers Plan was the “right Brexit for Britain”.

But heckling broke out on the Tory benches when Brexiteer Peter Bone claimed activists in his Northamptonshire constituency felt "betrayed" over what had emerged from Friday’s Cabinet summit. Colleagues cried out “shame” and “nonsense” at his remarks.

After Mrs May suffered constant Labour backering during her Commons statement, Jeremy Corbyn rose to claim the Tory Government was now in “crisis” following the resignations of Mr Johnson and Mr Davis.

The Chequers agreement, he argued, stood as a “shattered truce, a sticking plaster over the Cabinet's cracks in this Government".

To Labour cheers, he said: “For the good of this country and its people, the Government needs to get its act together and do it quickly and if it can't, make way for those who can."

Ian Blackford for the SNP said the Tory crisis had become a "national embarassment," saying it was hard to believe it had taken the PM "two years to put together a proposal...and two days for the Cabinet to fall apart".

Outside the chamber, Mrs May’s spokesman was adamant she would fight any challenge. Asked if there were a confidence vote, would she fight on, he replied: “Yes.”