Dominic Raab's resignation as Brexit Secretary was predicted more than two months ago by senior Government figures who described him as a ‘suicide bomber’ who always intended to blow apart Mrs May’s Brexit deal – and, in so doing, boost his own leadership ambitions.

Mr Raab said he had quit the Cabinet because he had come to the conclusion that the agreement which he had helped Mrs May to draw up presented ‘a very real threat to the integrity of the United Kingdom’ and that he could not ‘in good conscience’ support it.

Friends said he felt that he had been cut out of an 11th-hour editing of the deal, which contained unexpected changes in the wording that would tie the Government’s hands in future negotiations.

Former Brexit Secretary Dominic Raab resigned from Cabinet this week after claiming he could not support the Brexit deal his former department was responsible for negotiating

But Mr Raab’s intentions – and links to his predecessor David Davis, who also quit over Mrs May’s EU plans – were long a subject of suspicion in Downing Street and the Treasury.

A senior Government source said: ‘We always called him the suicide bomber and said DD was his controller. Raab just went through the motions of carrying out the negotiations until it suited him to detonate.

‘And it was completely dishonest for Raab to brief that he was resigning over not being informed of the final contents of the paper presented. He knew full well what was coming. He is just fundamentally unwilling to take any responsibility for anything hard or complicated.’

Friends of both Mr Raab and Mr Davis last night dismissed the claims as ‘ridiculous’. But Scottish Secretary David Mundell said Mr Raab’s resignation was about ‘manoeuvring and leadership’.

All that plotting must be thirsty work! It was a busy week for Dominic Raab, with a crunch Cabinet meeting on Wednesday, above, followed by his resignation. Which perhaps explains why he was spotted stocking up on beers in his constituency on Friday night...

Mr Raab’s move is widely seen to have given him ‘first mover’ advantage in any leadership contest caused by Mrs May losing a no confidence vote.

Two of his main rivals, Home Secretary Sajid Javid and Foreign Secretary Jeremy Hunt, expressed their concerns about Mrs May’s deal during Wednesday’s fiery Cabinet meeting – but both are still in their jobs and obliged by collective responsibility to defend the deal.

Brexiteer Tory MPs reserve particular ire for Mr Hunt, who they accuse of rejecting overtures from Michael Gove to join him in putting pressure on Mrs May to go to Brussels to try to renegotiate the deal. One said: ‘He is just a male Theresa May, a sell-out, no backbone.’

Mr Davis – who had hoped to be anointed automatically as caretaker leader if Mrs May was unseated – is now thought to be considering joining a Raab leadership bid instead.

Boris Johnson eyes Raab with deep suspicion, with one of his supporters saying: ‘This is no time for a novice’. Liz Truss, Chief Secretary to the Treasury, is also considering running. But friends indicate that she is most likely to act as ‘kingmaker’ in a contest.

Although Mr Javid’s allies have approached Ms Truss to join a putative leadership team she is understood to be ‘leaning towards’ the idea of joining Raab’s team – on the understanding that if he was elected he would go back to Brussels to renegotiate. However, this is rejected by Brussels. One EU source said: ‘There is no appetite for further concessions. What has been agreed is delicately balanced. The deal is the deal.’

Senior Tories such as David Davis, left, are believed to be plotting against Theresa May, right

The most recent rankings of potential leaders among Tory voters by the ConservativeHome website – assembled before last week’s drama – put Boris Johnson top, followed by Sajid Javid, David Davis, Jacob Rees-Mogg, Dominic Raab, Jeremy Hunt and then Michael Gove. Tory MPs will decide which two candidates go forward to party members for the final vote. But it is still far from clear whether there will be a leadership contest.

A former Tory party chairman told The Mail on Sunday: ‘If there is a no confidence vote, I think she will face it down and win.

‘She will have been inspired by the example of Jeremy Corbyn, who saw off a coup attempt by his MPs. She has a massive “payroll vote” of Ministers – over 100 of them – and paid vice-chairs who keep their jobs by voting for her. Also, and don’t underestimate this fact, she lives for the job – so has every incentive to persevere.’

The UK’s turmoil has dismayed Brussels. Some senior EU officials have even discussed delaying next Sunday’s Brussels summit, which is meant to finalise the Brexit deal, until after a Commons vote.

They say that if the deal is likely to be rejected, then next weekend’s summit would be a ‘waste of everyone’s time’.