Apologising to the Queen is bad but angering the electorate could spell the end for Boris Johnson

What is the so-called 'Operation Save Big Dog' plan - denied by Downing Street - to help Boris Johnson keep his job after the No10 parties scandal? ITV News Deputy Political Editor Anushka Asthana explains

When you need to apologise to the Queen, you know things are bad - and Conservative MPs know it, too.

When I spoke to many on Thursday, they had allowed their anger to die down, and were prepared to wait until Sue Gray delivers her judgement on Boris Johnson and the Number 10 parties.

On Friday that anger has flared up again. One MP told me it makes things “very much worse” and could speed up the problems for Johnson within his party.

Another said things had been “terminal” for some days – and that Monday could now become a key day.

He argued that MPs would spend the weekend hearing from constituents and Tory members and witnessing their fury. That would focus minds, ahead of a return to Parliament next week when one subject is likely to continue dominating in Westminster.

Other risky points for the prime minister will be when Gray reports (expected late next week at the earliest) and, if he gets through that, the May elections.

But one warned that waiting until May could look bad to voters – who will not appreciate the party hedging its bets until they test Johnson’s post-scandal electability.

Even those normally loyal have gone somewhat quieter, with a Cabinet source telling me ministers are reluctant to put themselves forward for media rounds.

They are too nervous of what is going to be revealed next, they said, arguing that Number 10 had “lost all authority”.

Meanwhile, MPs are chatting away about possible successors, as the Chancellor Rishi Sunak meets 100 MPs in a week to discuss the energy bill crisis, and foreign secretary Liz Truss woos colleagues with dinners.

Some 'red wall' MPs tell me they think that neither of them could win their seats, with names like Penny Mordaunt and Ben Wallace coming up (not that either has indicated they might run).

But some 'red wallers' did argue in favour of Sunak – saying he was incredibly popular on the doorstep as a result of his furlough scheme. Truss, meanwhile, has polled well on surveys by the Conservative Home website.

Johnson still hopes to save himself – with suggestions tonight that he will seek to get a number of others to quit in an attempt to remain in position. One report suggests the plan has been nicknamed Operation Save Big Dog – although that has been denied by Downing street.

Some MPs still think it's possible to save Johnson if the Gray report is at the most positive end of possibilities. But for others it's not.

A strategist with close links to the party argued that it was “game over” and there was now “no way back” for the prime minister. “He must go now or take the entire Tory party down with him,” they said.