Boris Johnson has not denied joking that he was at “probably the most unsocially distanced gathering in the UK right now” during a boozy mid-pandemic leaving do.

One of the most damaging pieces of evidence in the Privileges Committee’s interim report earlier this month was the allegation that the then-prime minister made the comment at a No 10 gathering in November 2020.

In his defence dossier, Mr Johnson said he did not recall making the remark, but failed to deny it.

He also claimed the quote was selective and the committee had missed out a line from the witness saying he only had a glass of water and left.

Mr Johnson wrote: “I do not remember saying the words quoted by (No 10 official) – and it seems unlikely given that it was, as (No 10 official) says, a small and impromptu event.

“But I might well have made observations in speeches about social distancing, and whether it was being perfectly observed. That does not mean that I thought the guidance was contravened.”

He added that he did not believe the guidance “required full social distancing at all times provided you did what you could overall”.

Mr Johnson also said: “What the Committee failed to record in the Fourth Report was the next line of [No. 10 official]’s statement: ‘he had a glass of water in his hand, made a short speech and then went up to his flat. He was the most sensible person there to be honest’.”

Mr Johnson allegedly made the statement at a leaving party for a No 10 special adviser on November 27 2020, weeks after ordering England’s second national lockdown.

Sue Gray’s report said Mr Johnson gave a short leaving speech at the apparently impromptu gathering, surrounded by up to 20 people, some of whom were drinking alcohol.

The Privileges Committee said it had received evidence that “there was no social distancing and people were standing 4–5 deep”.

At the time, indoor gatherings of two or more people were banned except for in certain circumstances such as for “work purposes”, and social distancing remained the rule in workplaces.

With several Downing Street leaving parties documented in Ms Gray’s report, Mr Johnson said he believed it was his “duty” as the prime minister to “say a few words of thanks” to those departing.

“I might raise a glass to honour a colleague, but that was it,” he wrote.

“When I looked around the room, I did not think anyone was breaking any rules or guidance: on the contrary, I thought that we were all doing our job.”

Mr Johnson’s 52-page written evidence was published on Tuesday, a day before he faces a live grilling by the cross-party group of MPs in a hearing that could decide his political fate.