The plan is expected to pass despite the Tory backlash because Labour has said it will support it.

Under the Government’s proposals, from 6am on Wednesday people will need to show proof of two jabs or a negative lateral flow test in order to enter nightclubs and large venues.

Sajid Javid, the Health Secretary, confirmed on Monday that once all adults have had a reasonable chance to receive a booster jab, three doses will be required for a valid NHS Covid pass.

Amid concerns of resignations, discussions took place over whether to offer wavering parliamentary private secretaries (PPSs), who are deemed members of the government payroll even though they are not paid, permission to be away from the Commons in order to miss the vote.

Several PPSs asked to go and campaign in North Shropshire, ahead of a tense by-election on Thursday, as a compromise in order to avoid backing the proposal or quitting.

Ultimately, however, the whips decided to take a robust line.

Rebels face ‘temporary halt to their careers’

“You can’t allow one to go and ask all the others to vote for it, it’s a slippery slope,” said a government source. The insider said ministerial aides had been reminded of their “obligations”, adding that to rebel would likely mean “a temporary halt to their careers” for which the Prime Minister would “probably not forgive them”.

Resentment among some PPSs that Angela Richardson was reinstated as a ministerial aide to Michael Gove after rebelling in the Owen Paterson sleaze row last month had “galvanised the whips office to be strict” on all further revolts, the source said.

It was claimed that pressure was applied to Tory trade envoys too, even though holders of the posts – a group that includes opposition parliamentarians – are not technically required to vote with the Government. The claim was denied by government insiders.

Cabinet ministers and whips also mounted a positive argument for Covid passports, sharing internal polling commissioned by the Cabinet Office showing the public favours Plan B and a cautious approach, it is understood.

In a sign the heavy lobbying was cutting through, one ally of Mr Johnson on Monday predicted that three PPSs at most would resign on Tuesday while it was now conceivable that none would quit at all.

It marked a significant fall from the previous tally of ministerial aides placed on “resignation watch”.

Mr Javid spent Monday briefing 10 concerned PPSs who had set up a WhatsApp group to discuss how to vote. It followed a personal ring-round by the Health Secretary and Maggie Throup, the vaccines minister, to potential rebels over the weekend.