James Slack, former director of communications for Prime Minister Boris Johnson, issued a public apology on Friday, regarding a party held at Downing Street on 16 April.
"I wish to apologise unreservedly for the anger and hurt caused. This event should not have happened at the time that it did. I am deeply sorry, and take full responsibility".
Slack said he could not elaborate on the details, as the information had been referred to Sue Gray's investigation into the parties held during the lockdown.
The party was held to mark the departure of Slack, who is now deputy editor-in-chief at The Sun, as well as the departure of one of the prime minister's personal photographers.
There reportedly were at least 30 staffers at the party, and they were drinking until late into the night. The event was held amid harsh pandemic restrictions on the eve of Prince Philip's funeral.
Britain's Prime Minister Boris Johnson speaks during a virtual press conference to update the nation on the status of the Covid-19 pandemic, in the Downing Street briefing room in central London on January 4, 2022.
© JACK HILL
Boris Johnson previously faced a public outcry when reports suggested that several gatherings were held at his office during the lockdown period. This includes a massive garden party for up to 100 people in 2020 that was allegedly attended by the PM himself and his wife Carrie Johnson. At the time, social mixing between households was limited to two people, who could only meet outdoors and with social distancing.
The opposition, as well as some Tories, urged him to resign, however, the government backed Johnson, who has repeatedly stressed he didn't violate the lockdown rules.