Opening the crunch hearing by a House of Commons committee, the ex-Conservative leader swore an oath on the Bible and declared that "hand on heart, I did not lie to the House".
The House of Commons Privileges Committee has published a fresh bundle of evidence, including photographs and statements from Johnson's close aides at the time, ahead of the oral evidence session.
Johnson is due to give oral evidence to the House of Commons Privileges Committee this week and made written submissions ahead of that, in which he criticises the panel for going "significantly beyond its terms of reference".
Liz Truss had the shortest tenure ever for a British PM, sparking memes and jokes on social media.
The embattled British prime minister rapidly lost favour in the Covid era, with the emergence of scandals like "Partygate".
Boris Johnson’s time as prime minister was marred by his handling of the coronavirus pandemic and a steady stream of ethics allegations, from alcohol-fueled government parties that broke lockdown rules to how he handled a sexual misconduct scandal involving a senior party lawmaker.
More than 40 of his Tory MPs have publicly called for Johnson's resignation as the party leader over the scandal of COVID law-breaking parties under his premiership at Downing Street, an issue which remains in the spotlight since the scathing findings of leadership failures in an inquiry by top civil servant Sue Gray.
UK Prime Minister Boris Johnson also unwittingly dug himself into another controversy by inaugurating a factory that makes the same machines that were used to demolish homes in Delhi.
A delay in the publication of the Sue Gray inquiry report into Partygate has taken the edge off those seeking to challenge Boris Johnson.
Essentially, a lot of partying and bragging about the partying, when the rest of the nation was home alone