BORIS Johnson has suffered a devastating blow in his bid to secure a do-or-die Brexit with the resignation of his brother Jo as one political opponent accused the Prime Minister of posing such a threat “even his own brother doesn’t trust him".

The UK Universities Minister admitted his dramatic exit from the UK Government was a result of being “torn between family loyalty and the national interest".

As the sensational development rocked Westminster, Mr Johnson was accused of being “willing to sacrifice anyone and anything on the altar of his ego and ambition”.

On a visit to a police academy in Yorkshire and ahead of a visit to Scotland today, Mr Johnson sought to downplay his younger brother’s decision, noting how Brexit was an “issue that obviously divides families and divides everybody".

The PM is believed to have frantically, and unsuccessfully, tried to talk his brother out of resigning in a phone-call on Wednesday night. But, afterwards, he did not mention the imminent political bombshell to even his closest advisers.

At the event in Wakefield, to launch his pledged recruitment drive for 20,000 new police officers south of the border, Mr Johnson’s Brexit line was repeated with vigour as the PM insisted he would rather be "dead in a ditch" than go to Brussels to ask for a further delay.

Earlier, the Government announced it would have another go on Monday at getting an early General Election on October 15 following its failure on Wednesday.

But at Westminster a deal was brewing between Labour and the SNP to block a snap poll before the October 31 Brexit delay date. Indeed, it was suggested the pact between the parties could lead to them uniting to call a no-confidence vote in Mr Johnson as early as Monday.

Splits were said to have emerged between the SNP in Edinburgh and London with party leader Nicola Sturgeon pushing for a snap election once the Brexit extension bill was passed. But MPs were more cautious and wanted to play a longer game.

Stephen Gethins, the party’s Europe spokesman, said: “We need to make sure that no-deal really is off the table. We can’t trust Boris Johnson one bit,” while his colleague Pete Wishart told MPs a general election was coming “but everybody has to be certain that their no-deal is dead and buried”.

Last night at the CBI annual dinner in Glasgow, Sir John Major intervened to launch an excoriating attack on Mr Johnson’s Government, demanding an end to the “threats and abuse” from Cabinet Ministers and Downing St advisers and that Dominic Cummings, his chief adviser, whom he branded a “political anarchist,” should be sacked.

As the atmosphere at Westminster continued to be dizzying, uncertain and fractious, another unexpected event took place: Jo Johnson’s resignation; not just from the Government but from politics.

In a tweet, the UK Universities minister, who had, at times, sat around the Cabinet table from his brother, announced: “It's been an honour to represent Orpington for 9 years & to serve as a minister under three PMs.

“In recent weeks I've been torn between family loyalty and the national interest - it's an unresolvable tension & time for others to take on my roles as MP & Minister. #overandout."

Mr Johnson, 47, is said to have been “upset about the purge of colleagues".

He is a pro-European and last year resigned as a minister in protest at Theresa May's Brexit deal. But he was reinstated in the summer after his brother took over in No 10.

The MP for Orpington in London has previously called for a second referendum, a position that set him at odds with the PM. He is expected to stand down at the next election rather than leave Parliament immediately and spark a by-election.

Tensions over Europe within the Johnson family are well-known; sister Rachel has joked: "The family avoids the topic of Brexit especially at meals as we don't want to gang up on the PM."

Nick Boles, the former Conservative minister, who resigned from the party to sit as an independent, hit out, saying: “Johnson is willing to sacrifice anyone and anything on the altar of his ego and ambition. His lust for power consumes everyone who stands in his way.”

Labour’s Angela Rayner noted: "Boris Johnson poses such a threat that even his own brother doesn’t trust him."

Nigel Farage, the Brexit Party leader, said Mr Johnson’s resignation showed the "centre of gravity in the Conservative Party is shifting rapidly".

While Matt Hancock, the Health Secretary, tweeted: “Gutted @JoJohnsonUK is leaving Government and Parliament. He has been a brilliant Minister and a true Conservative - part of our broad church.”

During his visit to Yorkshire – which No 10 billed as the first event of the election campaign – the PM responded to reporters’ questions about Jo Johnson by describing him as a "fantastic guy" and a "brilliant minister".

Acknowledging the familial split on Europe, he added: "What Jo would agree is that we need to get on and sort this thing out."

During the event as Mr Johnson answered questions, one of the female police cadets standing behind him appeared in distress and had to sit down.

Prompted by the audience in front of him, he turned and asked her: “Are you alright?" As the officer then took a seat with her head bowed, the PM said: "I'm so sorry. OK that is a signal for me actively to wind up."

Later, No 10 sources said the PM spoke to the officer and “apologised for keeping her waiting in the sun for so long”.

But Labour’s Yvette Cooper accused Mr Johnson of an "abuse of power" for using a backdrop of police officers for a "political stunt".

Today, Mr Johnson will travel to Aberdeenshire to meet local farmers and promote the Government’s announcement of a £211.4 million boost to the local industry. This will be made up of £160m in so-called “historic convergence funding” and an additional £51.4m over the next two years to help ensure funding for farming is fairly allocated across the UK.

The PM said: “For too long, Scottish farmers have been given a poor deal by the EU’s Common Agricultural Policy, which is why we are taking this opportunity to change things for the better. I made a pledge to resolve the historic funding gap for Scottish farmers and delivering on this promise has been a priority since I became Prime Minister.

“Today’s announcement was the first step in making sure future funding is fairly allocated across the UK, taking into account the unique farming environments in Scotland.”

He added: “Once we are out of the EU, we will have a historic opportunity to introduce new schemes to support farmers and we will make sure that Scottish farmers get a fairer deal.”

After his visit to the farmers in Aberdeenshire, Mr Johnson will travel to Balmoral to undertake the PM’s traditional annual visit to see the Queen at her Highland retreat. However, due to the political pressures back at Westminster, he will not stay for the usual full three-night weekend but merely stay over on Royal Deeside for a single night.

A No10 spokeswoman said: “The PM has accepted Her Majesty the Queen’s invitation to visit Balmoral. He will have an audience of Her Majesty on Friday followed by dinner, before returning to London on Saturday.”

In other developments -

*Michel Barnier, the EU’s chief negotiator, postponed a visit to Belfast on Monday, saying it would be an “inappropriate” time to visit and that Westminster had reached a "moment of truth”. The PM is due to be in Dublin on Monday for talks with his Irish counterpart Leo Varadkar.

*Jacob Rees-Mogg, the Commons Leader, was accused of making “absolutely disgusting” comments after he compared a pro-Remain doctor to the discredited Andrew Wakefield, who is widely blamed for the scare over the MMR jab.

*Michael Gove, the Cabinet Office Minister in charge of no-deal planning, said he would vote for Theresa May's final Brexit deal if MPs were given the chance to pass it but added the PM’s hoped-for agreement would be a "material improvement" on his predecessor’s.

*Ex-Cabinet minister Damian Green and leader of the One Nation Group of Tory MPs said: "I'm afraid it does look as though somebody has decided that the moderate, progressive wing of the Conservative Party is not wanted on voyage."

*Nick Hurd, the Northern Ireland Minister, became the latest Tory MP to announce he would not stand at the next General Election as he cited "the ongoing division over Brexit".

*Ex-Environment Secretary Caroline Spelman had earlier announced she too was standing down at the next election after months of abuse and death threats against herself, her family and staff over Brexit.