The data has sent ministers scrambling to dramatically expand the roll-out of third jabs in the coming weeks, with billions more pounds expected to be spent on the programme.

But Cabinet sources, government aides and senior MPs warned that ministers and Tory parliamentarians would not accept further measures until reliable data emerged showing the number of hospitalisations and deaths caused by the new variant.

South African hospitals have reported “far milder” symptoms from omicron and on Saturday, Eleanor Riley, a professor of immunology and infectious diseases at the University of Edinburgh, said: “If it is milder … it is possible that this could act as a natural vaccine, getting to those people who have so far been unwilling to be vaccinated.”

Ministers ‘will not tolerate’ more measures without clearer omicron data

As speculation mounted over a possible “Plan C” of measures, such as extending vaccine passport requirements to other venues and re-introducing 10-day isolation periods for contacts of Covid-19 cases, a Cabinet source warned that ministers would not tolerate more measures this week in the absence of clearer data about the risks of omicron.

“Certain Cabinet ministers” would be “a lot more robust” in the event of a push for further restrictions next week, the source said.

“If we end up on the slippery slope where one week we’re doing one thing and the next we’re doing more, that is where a fair few of the Cabinet will resist”.

Another government source said that Downing Street and scientists were imposing restrictions “seemingly from nowhere – without any data whatsoever.”

Michael Gove, the Levelling Up Secretary, was said by multiple sources to be pushing for further restrictions.

“He thinks what we’ve set out already won’t be enough and we will need to do more,” said a Whitehall source.

Prime Minister is a ‘cat with nine lives’

Amid growing talk about an attempt to unseat Mr Johnson as Conservative leader, one senior Conservative in the City described the Prime Minister as a cat with nine lives but insisted he had “only used up about five of them so far”.

Others insisted he was “nearer to seven or eight”.

Discussing the potential rebellion on Tuesday, one PPS told The Telegraph that, following anger over Mr Johnson’s handling of a series of scandals and domestic policies, “The truth is that the balance has now tipped.

“People are not going to do things for the sake of government jobs that aren’t going to be there in a year because there is going to be a leadership contest. I didn’t anticipate it coming this quickly.”

The MP added: “It’s quite hard to get people back from a place where they fundamentally don’t trust the [No 10] operation.”

In his article, Mr Baker, the deputy chairman of the Covid Recovery Group of MPs, said: “Of course, I will vote against all measures on Tuesday.

“But I cannot in good conscience stop there when we are falling into such a ghastly trap, creating a two-tier Britain where we turn back the clock and tolerate businesses turning away customers from communities which have shown an unfortunate hesitancy to take up the offer of a vaccine.”

He adds: “Conservatives shouldn’t limit the ability of young people to get on the housing ladder, yet we’re doing precisely this by allowing Government to spend far too much taxpayers’ money.”

A Downing Street source said: “We have said very clearly we’re not going to bring in more measures until we know more about the variant and have more data. We need to see the effect of plan B.”