Boris Johnson's leadership faced its most serious threat yet Tuesday after it emerged his private secretary invited over 100 people to a "bring your own booze" party at the British Prime Minister's official residence during a coronavirus lockdown.

Johnson, who won a landslide election victory in 2019, has faced intense scrutiny over the past month after a video emerged showing his staff laughing and joking about a different party held during a 2020 Christmas lockdown, also at Downing Street.

Revelations about a series of gatherings that took place in the heart of government have prompted widespread criticism, with opposition Labour Party leader Keir Starmer accusing Johnson of lacking the moral authority to lead the country.