Boris Johnson's biggest Commons rebellion - and why it matters

"The rebels are haemorrhaging."

So said one government minister on Tuesday evening as the prime minister addressed the 1922 Committee of Conservative backbench MPs.

Boris Johnson made a last-ditch effort to win over his party in the packed meeting just an hour before the Commons voted on new Covid regulations.

He promised MPs they would be consulted on any future restrictions if they were needed. He warned his party it had "absolutely no choice but to act" and that nobody could be sure Omicron would be less severe than other variants.

Mr Johnson had also spent the day phoning potential rebels, trying to win them over to the merits of Covid certification. Meanwhile, Prof Chris Whitty briefed MPs on the rise of Omicron - with a government loyalist predicting this would win some over.

Leading figures in government seemed to think their argument was working. One senior cabinet minister said on Tuesday evening that the PM's efforts had gone down well.

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Mr Johnson himself declared to journalists after the 1922 Committee that he had done his best to persuade his party.

It wasn't enough. Far from it.

The rebellion on Covid passes was far bigger than many had predicted and by some distance the biggest of Mr Johnson's premiership.

It's all the more significant because of the prime minister's efforts to limit the damage.

What will worry Downing Street is that the vote brought different wings of the Conservative Party together in opposition to the government's plans.

There was the Covid Recovery Group of backbenchers, who had long been sceptical of restrictions and had consistently voted against the government.

But there were also centrists like Damian Green - who told BBC Radio 4's World at One that the plans for Covid certification wouldn't work, saying: "It's a gesture. It's doing something for the sake of doing something."

Anti-Covid pass protesters say they don't work and infringe civil liberties

Then there were the likes of the Scottish Conservatives, who do not believe Covid passports worked in Scotland.

They didn't take part in the Commons vote because the measures only applied to England - but they made their opposition abundantly clear.

Aberdeenshire MP Andrew Bowie told me: "We need to stop lurching from a something must be done position. Vaccine passports do not work."

As well as the 99 confirmed Covid pass rebels, there were many more who sat on their hands.

One former minister, a Johnson loyalist while in government, said he had made plans to avoid having to back Covid passports.

We don't know for certain how many took a similar position, but it takes the number refusing to back Mr Johnson over the 100 mark.

A majority of MPs did ultimately back Covid certification and the measures will still be brought in in England.

But a prime minister with a majority of 80 was forced to rely on opposition votes to get his plans through. That raises two big questions.

The first: Is Mr Johnson's authority waning?

Number 10 has undoubtedly been battered and bruised by the controversies of the past fortnight.

But in the past, Mr Johnson has been able to persuade and cajole his MPs into backing him - often when they didn't want to. This time, it just didn't work.

Secondly, will Mr Johnson now have to think twice about introducing more restrictions if they are needed?

This point is more complicated because there are some MPs who didn't like Covid certification - but do back other measures to stop the spread of Omicron and may vote for more in future.

But one leading and long-standing Covid rebel called this vote a shot across Downing Street's bow - a warning of what might be to come if the government did opt for stricter restrictions in the coming weeks.

Two years ago, Mr Johnson won a general election which gave him the biggest Conservative majority since Margaret Thatcher.

After months of Brexit battles in Parliament, the assumption was December 2019 marked the end of mass Tory rebellions.

Tuesday's vote proved that wasn't the case.