BORIS Johnson’s working majority in the Commons was wiped out just hours before a crunch vote on Brexit last night when former minister Phillip Lee defected to the Lib Dems.

The move means that even with the support of the DUP’s 10 MPs Johnson has no majority while he tries to fight off a Tory revolt over measures aimed at blocking a No Deal Brexit.

His task became even more difficult after Lee dramatically crossed the floor of the Commons to the Lib Dems as Johnson delivered his first statement as Prime Minister to MPs yesterday afternoon.

Lee, a former Justice Minister and a medical doctor, said the party that he had joined more than 27 years ago was not the party he was leaving now.

“This Conservative Government is aggressively pursuing a damaging Brexit in unprincipled ways,” declared the Berkshire MP, who accused it of deliberately using a strategy of political manipulation, bullying and lies.

“It is putting lives and livelihoods at risk unnecessarily and it is wantonly endangering the integrity of the United Kingdom. More widely, it is undermining our country’s economy, democracy and role in the world,” he added.

He later told Sky News that the “straw that broke the camel’s back” was when his colleague, fellow MP Jacob Rees-Mogg, told another doctor that he was “shameful” for raising concerns about the effects of a No-Deal Brexit on medical supplies.

The Leader of the House and hardline Brexiteer told a medical professional, who was involved in No-Deal Brexit planning, that he was “fear-mongering” during a live LBC Radio phone-in.

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Dr Lee told presenter Kaye Burley: “I haven’t left my party, my party has left me”, adding that he suspected several of his colleagues would be following in his footsteps.

Jo Swinson, the LibDem leader, welcomed Lee to her party on social media, tweeting: “Welcome @DrPhillipLeeMP - you have joined us at the most crucial time. I look forward to working with you to prevent a disastrous Brexit and to fight for a fairer, more equal society.”

The National: Jo Swinson welcomed Lee after he defected to the LibDem partyJo Swinson welcomed Lee after he defected to the LibDem party

Conservative rebels have been told they will have the whip removed and will be not allowed to stand as Tory candidates in the next election.

Earlier yesterday ex-Chancellor Philip Hammond, who has been co-ordinating the rebels efforts, raised the prospect of a legal fight if he was deselected.

Asked on Radio 4’s Today programme whether Downing Street had the power to prevent him from standing as a Tory at the next election, said: “I don’t believe they do and there would certainly be the fight of a lifetime if they tried to.”

Asked whether he would be prepared to take such a fight to the courts, he said: “Possibly. A lot of my colleagues have come under immense pressure. Some have responded to that by saying ‘enough, I’m going’. That is not going to be my approach. This is my party. I have been a member of this party for 45 years.”

In what was seen as a swipe at the Prime Minister’s controversial right-hand man, Dominic Cummings, he said: “I am going to defend my party against incomers, entryists, who are trying to turn it from a broad church to narrow faction.

“People who are at the heart of this government, who are probably not even members of the Conservative Party, who care nothing about the future of the Conservative Party, I intend to defend my party against them.”

The former foreign secretary said it was his understanding that Cummings was “not and never has been” a party member.

“I haven’t heard a denial from Downing Street, but perhaps we will hear one if that is not the case,” he added.

Former ministers David Gauke, Rory Stewart, Nicholas Soames (a grandson of Winston Churchill) are among the other key Tory rebels.