Details have emerged of what appears to be another alcohol-fuelled social event inside Downing Street during lockdown, one that was seemingly not investigated by police or the official civil service investigation. According to the Mirror, between 30 and 40 staff drank alcohol and ate takeaway snacks to mark the final press briefing conducted by Boris Johnson’s then-spokesperson James Slack, on 17 November 2020. A photograph obtained by the paper appears to show an official setting out bottles of wine and Champagne-type drinks. The picture was reportedly sent to No 10 staff on a WhatsApp group, in response to a message saying: “Time to open the Covid secure bar.” The photo was then posted as a reply with the message: “The bar is open.” Other messages reported by the Mirror seemingly demonstrate premeditation in socialising, with one referring to “Wine Time Tuesday”, and others discussing going to buy “reinforcement booze”. One official says: “If someone can help me carry it I’m happy to go.” The alleged event was four days after the leaving drinks for Lee Cain, Johnson’s head of communications. On Monday, ITV News obtained images showing the prime minister at the event, raising a glass and seeming to toast Cain and make a speech. Those images have placed pressure on the Metropolitan police to explain why Johnson was not fined for attending the 13 November gathering, when others there were. The 17 November event was not among gatherings investigated by the Met, and was not listed among those examined in the interim report into lockdown-breaching parties by the senior Cabinet Office civil servant Sue Gray. Her full report is expected to emerge on Wednesday. Slack, who was a civil servant rather than a political appointee like Cain, was chosen to replace Cain as head of communications. The 17 November drinks were held to mark the last time that, as Johnson’s official spokesperson, he spoke to the media at the daily lobby briefings, according to reports. At that time, because of the lockdown, the briefings were being held virtually rather than in person. Slack left No 10 in April 2021. That leaving party, held the day before Prince Philip’s funeral while indoor social mixing was still barred, was reported and investigated. He is now deputy editor of the Sun. Evidence of what appears to be yet another social event, and one planned in advance, puts further pressure on Johnson ahead of Gray’s findings, amid reports more Conservative MPs could be submitting letters of no confidence in the prime minister. If Gray’s full report is released on Wednesday, it would most likely be submitted to Downing Street in the morning and published shortly afterwards, with Johnson promising to give a statement to parliament and answer questions from MPs later that day. No 10 have said Johnson would then aim to hold a press conference. A No 10 spokesperson said: “As part of their investigation the Cabinet Office team were able to speak to No 10 staff to establish the facts on what happened during this period. Both they and the Met Police have had access to all information relevant to their investigations, including photographs. “The Met have concluded their investigation and Sue Gray will publish her report shortly, at which point the prime minister will address parliament in full.” Slack was contacted for comment.