Pressure mounted on U.K. Prime Minister Boris Johnson after a video emerged showing key aides joking about a party at Downing Street last Christmas at a time when such gatherings were banned.

The video, obtained by ITV News and which ITV said was recorded four days after the alleged event, shows Johnson’s then press secretary, Allegra Stratton, rehearsing for a TV media briefing and saying there was "definitely no social distancing” when asked about a party.

A backlash has been growing over whether Johnson’s own officials held a party at Downing Street last year in breach of the government’s own coronavirus rules, and the episode has cast further doubt over the integrity of Johnson’s administration after a rocky period.