The top civil servant will no longer lead a Whitehall investigation into alleged Christmas parties in Number 10 after he was revealed to have been aware of
a separate party in his own office in December last year.

Cabinet Secretary Simon Case has removed himself from his role in heading the probe into claims of parties being held in Downing Street and other government buildings last year in alleged breaches of COVID lockdown rules.

It comes after it emerged a festive event was held in Mr Case’s own office in December last year.

A Number 10 spokesperson said: “To ensure the ongoing investigation retains public confidence the cabinet secretary has recused himself for the remainder of the process.

“The work will be concluded by Sue Gray, second permanent secretary at the Department for Levelling Up, Housing and Communities.

“She will ascertain the facts and present her findings to the prime minister.”

Mr Case was appointed to lead the investigation only nine days ago.

The probe was announced by Prime Minister Boris Johnson after a video emerged of Number 10 officials joking and laughing about a Christmas party said to have taken place on 18 December 2020.

What was the ‘Christmas party’ held in Case’s office?

The Cabinet Office earlier on Friday confirmed a virtual quiz was held on 17 December 2020 for members of Mr Case’s private office.

Sky News understands the event was described as a “Christmas Party” in the diary and involved six people in the office – those who had already been on a rota to be in the office – and around six people taking part at home.

The event lasted an hour with people enjoying snacks and drinks at their desks.

Although Mr Case did not take part, he is understood to have walked through the office to get to his personal office and so was aware of what was happening.

At the end of the day, he walked out and thanked staff in an address lasting five to ten minutes.

On 16 December last year, London went into Tier 3 COVID restrictions, which forced pubs and restaurants to close and banned different households from mixing indoors.

A Cabinet Office spokesperson said: “Staff in the cabinet secretary’s private office took part in a virtual quiz on 17 December 2020.

“A small number of them, who had been working in the office throughout the pandemic and on duty that day, took part from their desks, while the rest of the team were virtual.

“The cabinet secretary played no part in the event, but walked through the team’s office on the way to his own office.

“No outside guests or other staff were invited or present. This lasted for an hour and drinks and snacks were bought by those attending.

“He also spoke briefly to staff in the office before leaving.”

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The SNP’s Westminster leader Ian Blackford had earlier demanded the cabinet secretary be suspended and his investigation into alleged Downing Street parties be handed over to a judge.

Who will now lead the investigation into party claims?

Ms Gray is a long-serving civil servant who was previously the government’s ethics chief.

As director general of propriety and ethics in the Cabinet Office, she led an investigation into former prime minister Theresa May’s deputy, Damian Green.

It prompted Mr Green’s sacking in 2017 after he was found to have lied about pornograhy being discovered on his House of Commons computer.

Ms Gray has previously been described, in the memoirs of former Liberal Democrat cabinet minister David Laws, as the person who “runs Britain” and the “real leader” of the UK.