Mr Johnson used his decision to quit as Foreign Secretary to declare war on her Chequers plan for leaving the EU.
Warning that the UK was heading for colonial status, he said the Brexit dream was ‘dying – suffocated by self-doubt’.
He claimed Mrs May was sending negotiators ‘into battle with the white flags fluttering above them’ and surrendering control to Brussels. Following a chaotic day of resignations and rumours, Downing Street is now braced for a potential leadership challenge.
Sources insisted the Prime Minister would stand and fight for the national interest while her allies derided Mr Johnson, saying he offered no solutions on Brexit.
Boris also faced criticism in many quarters for taking the time to stage the photos of himself signing the resignation letter and was branded a 'poundshop Churchill'.
In a reference to his decision to resign only after David Davis had quit as Brexit Secretary on Sunday night, one May loyalist said: ‘There’s not much honour in being second over the top.’
Mrs May also swiftly reshuffled her cabinet, bringing in Jeremy Hunt from Health to replace Boris as Foreign Secretary and Dominic Raab to replace Mr Davis.
But, in a significant intervention, Jacob Rees-Mogg last night backed Mr Johnson, saying he would make a ‘brilliant’ prime minister.
Mr Johnson was branded a 'poundshop Churchill impressionist' for staging the photos by Lib Dem MP Layla Moran, who accused him of 'running away like a coward' after he sensationally quit the Cabinet.
Slamming the photos, Ms Moran, a leading member of the anti-Brexit group Best for Britain, said: 'This staged resignation photograph is pathetic. This man is a poundshop Churchill impressionist. Its just very sad.
'But Boris is doing what he does best: when the going gets tough he runs away like a coward.
'He did it over Heathrow and he's done it today. Rather than fight for the country he yet again cares only for his own self interest.
'But at least he will have a little memento of the day his dreams came crashing down around him.'
Labour's David Lammy said: 'The fact that Boris Johnson arranged for a photoshoot of himself signing his resignation letter for the front pages tells us everything we need to know about him.
'Self-obsessed, vain egomaniac devoid of substance caring only about himself and advancing his career. Good riddance.'
Sam Macrory, an ally of Nick Clegg, said: 'We all know that Boris Johnson’s decision to quit is absolutely not about one man and his personal ambitions, but I’m struggling to think of another time where a Secretary of State called in the photographers to record the moment a resignation letter was signed.'
Gavin Sinclair said: 'This sums up Boris - has a senior minister ever called in a photographer before resigning...and just before the PM’s statement to the Commons?!'
And Jon David Ellis criticised Mr Johnson's behaviour in the aftermath of the Novichok poisonings, saying: 'Boris literally posed with his resignation letter. Hours after a British citizen died from a foreign agent he chooses self image over basic dignity.'
More than 80 MPs attended a meeting of the pro-Brexit European Research Group, which Mr Rees-Mogg leads, in order to attack Mrs May’s Chequers plan. ‘This has got to be killed and it’s got to be killed before recess [in two weeks’ time],’ said one attendee.
Another Eurosceptic confirmed MPs were writing to the Tory 1922 Committee backbench group to trigger a no- confidence motion.
One said: ‘It’s over now. She’s done. It would be good if it were done quickly. I want to know who will be standing against her. We need to establish a new government because this offer is indefensible’.
One MP told the 1922 Committee that Mrs May had orchestrated a ‘Remain coup’ at Chequers on Friday. All four ‘great offices of state’ are now held by those who campaigned for Remain.
Friends of Mr Johnson, whose aide Conor Burns also resigned, were tight-lipped last night about his next move. But his resignation letter offered no support for Mrs May and, unlike Mr Davis, he did not urge MPs to back her.
Home Secretary Sajid Javid was among those to praise Mr Johnson yesterday, saying he would miss his ‘Reaganesque optimism and passion for global Britain’. On a day of turmoil at Westminster:
Eurosceptic MPs said more ministers would resign unless Mrs May backs down and abandons her Chequers plan;
It was rumoured the Eurosceptics are close to gathering the 48 names needed to force a vote of confidence in Mrs May;
Mr Davis stepped up his attack on Mrs May’s tactics, saying ‘we are giving too much away too easily – and that is a dangerous strategy’;
Steve Baker, who quit as Brexit minister, said the Establishment was trying to block Brexit;
Jeremy Hunt took over as Foreign Secretary, while Matt Hancock succeeded him as Health and Social Care Secretary;
Mr Davis’s former chief of staff Dominic Raab replaced him as Brexit Secretary;
Downing Street was forced to deny that Mrs May will offer ‘preferential’ access to the UK jobs market to EU citizens;
No 10 admitted that the customs arrangements signed off at Chequers may not be fully ready before the next election in 2022;
Mrs May told Tory MPs they had a duty to stick together to keep Jeremy Corbyn out of Downing Street.
In the Commons yesterday Mrs May paid tribute to both Mr Davis and Mr Johnson, who she said had displayed ‘passion’ for the Brexit cause. But in her reply to Mr Johnson’s attack last night, the PM noted that he had initially backed the plan at Chequers last week, reportedly choosing to toast her success with champagne.
Mrs May said she was ‘sorry – and a little surprised’ to receive his resignation ‘after the productive discussion we had at Chequers’.
One of her allies said: ‘For all the flowery language in his letter, what is conspicuous by its absence is anything resembling an alternative plan.
‘He moans about all these things but there is no sense of how he might achieve a different outcome. That is the difference.’
Addressing the 1922 Committee, the Prime Minister acknowledged the controversy the Chequers deal had caused, but told MPs: ‘To lead is to decide.’ Outside the meeting, her supporters claimed she was in a better position following the resignations.
‘She is strengthened by all of this – it helps her,’ said Solicitor General Robert Buckland. ‘She has made decisions and the consequences are that some people feel they cannot be bound by collective responsibility, respect to them for resigning, but she has shown leadership.
‘This idea she is some sort of vacillator who cannot make her mind up and wants to keep everybody in the tent – no – she is showing leadership.’
Tory MP James Heappey said there was ‘huge support’ for Mrs May at the 1922 Committee. He said Brexiteers seeking to depose her ‘can do their worst, but it won’t be enough’.
In the Commons pro-Remain Tories, including Anna Soubry and Nicky Morgan, backed Mrs May. But the Prime Minister faced direct challenges from a string of Eurosceptic Tories.
Mr Rees-Mogg said her Brexit promises ‘have been watered down to the point that we are, or would be, in a semi-suspended state of membership of the European Union’.
He said the Cabinet resignations ‘really undermine the credibility of what was agreed at Chequers’.
Andrea Jenkyns, who quit the government to speak out on Brexit last month, said she would be writing a letter of no-confidence in Mrs May.
She said Mrs May’s premiership ‘is over... there’s a feeling we need a PM who believes in Brexit’.
Senior Conservative Sir Bernard Jenkin warned there had been a ‘massive haemorrhage of trust’ as a result of the direction the PM was taking and said it ‘may well come’ to a vote over her leadership.
In the Commons, Peter Bone accused Mrs May of betrayal. Mr Bone, who faced cries of ‘shame’, told the PM that activists in his Wellingborough constituency were questioning why they were still campaigning for the party.
Mrs May replied: ‘This is not a betrayal. We will end free movement. We will end the jurisdiction of the European Court of Justice.
‘We will stop sending vast sums of money to the European Union every year.’
Jeremy Hunt - Britain's longest ever serving Health Secretary - was promoted to head the Foreign Office after Boris Johnson's shock resignation.
Theresa May moved to reshuffle her frontbench team after a day of high political drama which threatened to bring her premiership crashing down.
Earlier she faced down her critics at a crunch meeting with her MPs - known as the 1922 committee - in Parliament, warning them they risk handing the keys of No10 to Jeremy Corbyn if they oust her.
Mr Johnson's departure fuelled feverish discussion about whether mutinous Tory MPs will move to topple Mrs May by sending in letters of no confidence.
But the PM has insisted that she will stay on and fight if a leadership contest is triggered.
The promotion of Mr Hunt - a Remainer who now says he would back Brexit - comes weeks after he secured a £20billion a year funding boost for the NHS to mark its 70th birthday.
Culture Secretary Matt Hancock will move to head up the health service, attorney general Jeremy Wright has become the new Culture Secretary while Brexiteer Geoffrey Cox is being made Attorney General in the shake-up.
Earlier this year Mr Hunt fended off efforts by the PM to move him from the health brief to become Business Secretary - telling her he was determined to stay on and finish the job he had set himself as Health Secretary.
It came hours after Mrs May promoted Brexiteer Tory MP Dominic Raab to the post of Brexit Secretary as Mr Davis' replacement.
Unlike his predecessor, Mr Hunt backed Remain in the EU referendum - but he has said he would now vote for Brexit because he has grown fed up with the 'arrogance' of Brussels.
The PM moved to shore up her support among the Tory backbenches by defending her Brexit plans in the Commons chamber and a packed meeting of the parliamentary party which took place immediately afterwards.
She warned mutinous Tories threatening to mount a revolt to out her that they risk letting a hard left Corbyn- led Government.
And she was given a reprieve tonight with news she will not face an immediate vote of no confidence.
The rare bright spot for the PM came as she issued a defiant message at a stormy session of the Tory 1922 committee in Parliament, with her premiership hanging by a thread.
Mrs May told the gathering that 'to lead is to decide' and raised the prospect of the Labour leader imposing a left-wing revolution on the country.
And in a boost for the embattled PM, the chairman of the powerful 1922, Sir Graham Brady, is said to have confirmed at the session tonight that currently he has not received the 48 letters from MPs that would trigger a no-confidence vote.
After the meeting, solicitor general Robert Buckland told journalists that Mrs May had received strong support from the party rank-and-file.
He said: ‘She talked about Jeremy Corbyn, she talked about the alternative being to deliver the country to the sort of Government people didn’t vote for and any Conservative voter would be repelled by.’
Mr Buckland insisted Mrs May could emerge strengthened from the furore, comparing the turbulent events to the crises which faced German Chancellor Angela Merkel in her early years in office.
He said: ‘I think she is strengthened by all of this, I think it helps her.
'The most striking remark she said was “to lead is to decide”.'
Tory MP Geoffrey Cox - a Brexiteer who has been promoted to Attorney General in today's reshuffle - said many Eurosceptics inside the meeting urged the PM to stay on and lead them through Brexit.
He said: 'I regret Boris and David have gone, but I think they were wrong - they should have stuck in and make this deal successful.'
He said the third way deal Mrs May has put forward represents a 'giant step' on the road to Brexit.'
But Jacob Rees-Mogg, a Tory MP and leader of the European Research Group - the powerful group of backbench Tory MPs - said the PM must ditch her Chequers plan.
He said: ‘You see that those supporting Remain two years ago are supporting quasi Remain now…the key question for today is does the rather bad Chequers deal go ahead.’
And he warned that if the Tory party splits along the two wings of Brexiteers vs Remainers - the fault will lie squarely with Downing Street.
He said: 'If the Government plans to get the Chequers deal through on the back of Labour Party votes then 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 Conservative party across the country.’
Boris Johnson’s dramatic resignation came after he refused to put his name to a Downing Street-drafted article supporting the Chequers agreement, it emerged last night.
Mr Johnson, who quit the Government yesterday, had appeared to have fallen into the line with the negotiating strategy announced on Friday evening – despite apparently referring to it as a ‘t**d’.
He was even said to have congratulated the PM at dinner for securing Cabinet agreement. But on Saturday he refused to sign off a joint newspaper article with the Remain-backing Chancellor Philip Hammond – a long term Remainer – supporting the deal.
A friend said Mr Johnson took one look at the article and said: ‘I can’t put my name to this.’ A text drafted by No 10 was passed to the Treasury, then sent on to the FCO on Saturday. But seeing the consequences of the deal in black and white made him realise he would have to quit, allies revealed.
‘At that point he knew it was indefensible,’ the friend said.
On Sunday a series of articles purporting to be written by Cabinet ministers supporting the deal were placed in newspapers. Both Mr Johnson and Brexit Secretary David Davis were conspicuous by their absence.
By yesterday, according to allies, Mr Johnson was ‘racked with doubt’ about whether to stay in the Cabinet at all and concluded he simply couldn’t improve the deal from inside government.
He telephoned Downing Street yesterday lunchtime and told them he planned to announce his resignation in the evening.
But No 10 refused to allow him that luxury and – in a clear attempt to spike his guns – made the unusual decision to announce his departure in a short statement at 3pm, before Mr Johnson had even finished composing his resignation letter.
It emerged hours later, warning that the UK was heading for a ‘Semi-Brexit’ as a ‘colony’ of Brussels and that the dream of the Leave campaign – to take back control of our democracy – was ‘dying’.
In her icy reply last night, the Prime Minister said she was ‘a little surprised’ to see Mr Johnson departing the Government after the Cabinet signed off on her deal at Chequers on Friday. She suggested he was going back on his word.
But after Mr Davis quit the Government at midnight, speculation quickly swirled around Westminster that Mr Johnson would follow. The rumours soon reached fever pitch when he failed to attend a meeting of the Government’s emergency Cobra committee at 1pm to discuss the Salisbury poisonings.
He had also been expected to host, but was notably absent from, the Western Balkans Summit in London’s Docklands yesterday afternoon, involving ministers from several EU states.
Instead, he spent the day locked in talks with advisers at his official residence, Carlton Gardens. As the atmosphere turned febrile, it was suggested No.10 had enraged Mr Johnson by offering his job to Mr Davis in a desperate attempt to get him to stay inside the Cabinet, something denied by Theresa May’s aides.
Allies of the Foreign Secretary insisted last night that neither this, nor leadership ambitions, was ultimately a factor in his decision to leave Indeed, when his resignation letter was finally released, it was a vivid deconstruction of the Prime Minister’s Brexit strategy. Savaging the PM’s Chequers deal, he said vast swathes of the economy would be ‘locked in’ to Brussels rules but with no influence over them.
He also launched a scathing attack on the PM personally, accusing her of being ‘suffocated by needless self doubt’ and of running up the white flag to Brussels.
And he warned this ‘disturbing’ opening bid could be followed by further concessions on immigration and money ‘for access to the single market’.
Unlike Mr Davis – who notably backed Mrs May staying in office in interviews yesterday – Mr Johnson made no such offers of support.
Mr Johnson wrote: ‘Brexit should be about opportunity and hope. It should be a chance to do things differently, to be more nimble and dynamic, and to maximise the particular advantages of the UK as an open, outward-looking global economy. That dream is dying, suffocated by needless self-doubt.’
Mr Johnson said the failure to prepare for ‘no deal’ means ‘we appear to be heading for a semi-Brexit, with large parts of the economy still locked in the EU system, but with no UK control over that system.’
And he condemned Mrs May’s customs proposals, the Facilitated Customs Arrangement, calling it an ‘impractical and undeliverable customs arrangement unlike any other in existence.’ In his letter, Mr Johnson accepted that on Friday he had congratulated the PM on ‘at least reaching a Cabinet decision on the way forward’. He then added: ‘As I said then, the Government now has a song to sing. The trouble is I have practised the words over the weekend and find that they stick in the throat.’
Last Thursday night, David Cameron made an extraordinary appeal to Mr Johnson not to resign.
The former prime minister, acting with the blessing of Mrs May, met for drinks with his fellow Old Etonian at a London club just hours before the make-or-break summit.
Last Wednesday other pro-Leave cabinet ministers met Mr Johnson in the Foreign Office as details of Mrs May’s proposals leaked out. Penny Mordaunt, Andrea Leadsom, Esther McVey, Liam Fox, Chris Grayling, Michael Gove and David Davis – as well as Gavin Williamson discussed the plan. A similar group met the next day to plan tactics for Chequers in an attempt to push an alternative plan.
This article has been adapted from its original source.
© Associated Newspapers Ltd.