If Boris Johnson’s premiership is brought to a humiliating close in the coming days, it will not only be because he allowed Downing Street’s boozy lockdown parties to happen on his watch – but because he lied about them. When allegations of parties first emerged, Johnson told MPs in the House of Commons that Covid guidance “was followed completely in No 10”, and on another occasion – vehemently – that he had been “repeatedly assured” there were no parties. Both of those assertions now seem increasingly hard to believe, as has been evident in Johnson supporters’ tortuous efforts to defend him. Slavish loyalist Conor Burns plumbed new depths of absurdity this week by saying the prime minister was “ambushed by a cake”. On Wednesday Labour claimed there was further evidence of lies when newly released Foreign Office emails appeared to contradict Downing Street’s insistence that Johnson did not personally authorise the controversial rescue of cats and dogs from a British animal charity in Afghanistan. Even those cabinet ministers who have backed him in recent days have stressed the sanctity of the ministerial code, which says bluntly that “ministers who knowingly mislead parliament will be expected to offer their resignation”. Citing that rule on Wednesday, Labour leader Keir Starmer called on Johnson to resign immediately. But judging by the prime minister’s half-apology for attending the “bring your own booze” party in May 2020, which he insisted he believed was a “work event”, he appears likely to argue that if he did mislead parliament, he did so unwittingly. Amber Rudd resigned as home secretary in 2018 when she discovered she had “inadvertently misled” the home affairs select committee but Johnson appears unlikely to take the same approach. His allies have insisted he will fight any vote of no confidence. Those who have worked closely with Johnson over the years say fibbing is an entrenched part of his psychological makeup – and his political toolkit. His first instinct, when backed into a political corner, is to tell a wilful untruth, they say. Indeed, they suggest that, over time, Johnson comes to believe the version of reality he weaves for himself as he fibs his way out of trouble. “It’s almost a superpower in a way,” one former colleague said with something approaching awe. He has twice been sacked in the past for lying. In 1988, the Times got rid of him after he made up quotes in a news story. He later conceded that he had “mildly sandpapered something somebody said”. As an MP in 2004, he was dispatched from the Tory frontbench, not for having an affair but for failing to come clean about it. He had described the claims of a long-running relationship with Spectator colleague Petronella Wyatt as “complete balderdash”. During the 2019 Tory leadership contest, Conservative MPs who compared notes afterwards found he had made completely contradictory promises to them about what stance he would take on particular policies. None of that appeared to matter too much when the odd fib was part of the devil-may-care persona his own MPs believed made Johnson the “Heineken politician”, reaching groups of voters the Tories had previously struggled to win over. And it was of a piece with the ruthless approach he and his band of Vote Leave veterans took to bulldozing Brexit through – even when that meant proroguing parliament, or taking the whip away from senior and long-serving MPs. Little more than two years after Johnson secured a thumping parliamentary majority and did indeed “get Brexit done”, he may be felled by the very maverick qualities that helped him into Downing Street – not least his seeming inability to stick to the truth.