Keir Starmer has accused Boris Johnson of contaminating faith in democracy by trying to “devalue the rules so they don’t matter to anyone any more”, and hit out at the government for being too preoccupied with party allegations to deal with a looming cost-of-living crisis. The Labour leader said ministers were “intent on saving themselves, not serving the country” and called out Johnson for making “repeated lies from the dispatch box”. After it was revealed 12 gatherings in Downing Street and across Whitehall were being investigated by Scotland Yard, Starmer said No 10 was “in paralysis” and suggested he thought Johnson had knowingly broken strict Covid laws. The prime minister has said people should wait for the Met’s inquiries to conclude, but is under mounting pressure from Tory MPs who are continuing to submit no-confidence letters. In a speech on Thursday at Edelman, Starmer vowed that he would lead a Labour government that abided by the “Nolan principles”, seven key standards that holders of public office are already expected to observe: selflessness, integrity, objectivity, accountability, openness, honesty and leadership. “I shouldn’t have to pledge to honour these principles but, sadly, I feel I do,” Starmer said. “It isn’t that the prime minister thinks the rules don’t apply. He absolutely knows that they do. “His strategy is to devalue the rules so they don’t matter to anyone any more. So that politics becomes contaminated. Cynicism and alienation replace confidence and trust. So that the taunt ‘politicians are just in it for themselves’ becomes accepted wisdom. “It is a strategy to sow disillusion; to convince people that things can’t get better, government can’t improve people’s lives, progress isn’t possible because politics doesn’t work. “But I’m not going to play the prime minister’s game. I simply refuse to accept that Britain can’t be governed better than this.” Starmer said he would not “simply shrug my shoulders at the dishonesty and disrespect on the basis that it is ‘priced in’” with Johnson. He also accused the prime minister of issuing “repeated lies from the dispatch box” in parliament – a statement MPs are usually unable to make from the Commons given the strict rules about not accusing someone else of deliberately misleading the house. It comes after Johnson vowed to fight on as prime minister and lead the Tories into the next election, which could be as late as 2024, suggesting he hoped to remain in post until 2029. However, a Conservative MP and former cabinet minister said Johnson had already lost the trust of “large parts of the population”. David Davis, an ex-Brexit secretary, told Times Radio: “The problem is the prime minister is losing or has lost the trust of a large part of the population, which is important for the administration of law, that people should follow what the government says, and so on.” Three further MPs announced publicly they had submitted no-confidence letters in Johnson on Thursday, meaning the numbers are gradually increasing toward the threshold of 54 needed to trigger a ballot on the prime minister’s premiership. Johnson has brushed off suggestions he attended any gatherings that constituted parties, though apologised earlier this week after the interim findings of a report were published by senior civil servant Sue Gray. Gray’s report has not been published in full because of the ongoing Met inquiry, but a brief “update” on her investigation criticised “failures of leadership and judgment” at the top of government. Johnson said he was “sorry for the things we simply did not get right and sorry for the way this matter has been handled” and that it was “no use” trying to argue whether events broke the rules or not because he understood “the anger that people feel”. He also spoke of reviewing the civil service and special adviser codes of conduct – but neglected to include the ministerial code.