Boris Johnson has repeatedly refused to say that he would resign if he is fined by police over Partygate in a tense interview.
The Prime Minister was grilled over his own future after he submitted a legal questionnaire to Scotland Yard on Friday as part of the force's probe into rule-breaking parties.
Officers are investigating 12 lockdown gatherings in Downing Street and Whitehall, including six events Mr Johnson is believed to have attended.
