Speaking to Kay Burley, Sir Keir said many members of the public will have felt "anger, grief and guilt" when looking back at how they obeyed COVID-19 restrictions over the last two years and the sacrifices they had to make.

'Positive' mood among Tory MPs as PM appears to have staved off immediate threat - politics live

Minister claims PM can't answer specific questions over partygate allegations

He said Boris Johnson is "debasing the office" of prime minister and has "got to go" in the wake of the release of a partial version of the Sue Gray report, which he described as being as "damning as it could be".

The senior civil servant leading the Cabinet Office inquiry into the partygate allegations said Downing Street lockdown gatherings represented a "serious failure" and are "difficult to justify".

The PM apologised to the Commons and promised a shake-up of Number 10, insisting: "I get it and I will fix it."

Analysis: Release of Gray report is far from the end of the affair

Sir Keir's comments come after the deputy prime minister claimed Mr Johnson cannot answer specific questions about lockdown parties in Downing Street because he does not want to prejudice the police investigation.

"If he does start answering specific questions that have been referred to the police, he will be accused, in fact fairly and rightly, of prejudicing or preventing or interfering in that investigation," Dominic Raab told Kay Burley.

Mr Raab said it was right that police were now given the "time and space" to carry out their investigation.

"No one wants that investigation to conclude more swiftly than us. But it must be done on their terms," he said.

His response came after he was asked whether the PM was at an event in the Number 10 flat in November 2020, one of the 12 gatherings the Metropolitan Police is investigating.

Raab's defence dismissed as 'nonsense'

The force said on Monday that it has received more than 300 photos and 500 pieces of paper as part of its inquiries into events during COVID-19 restrictions in 2020 and 2021.

But Sir Keir said Mr Raab's stance was "nonsense" and "bordering on the ridiculous", accusing the PM of "forcing all of his frontbenchers onto your programmes and others to make complete fools of themselves, peddling these absurd defences".

SNP Westminster leader Ian Blackford told Sky News that people are "outraged by a prime minister that simply won't accept responsibility".

Speaking to Kay Burley, he said Mr Johnson has "demeaned the office and he should have gone by now".

Mr Blackford was thrown out of the Commons on Monday for accusing the PM of having "wilfully misled" MPs over the partygate row.