Simon Case has been informed about an alleged, and until now unreported, gathering at No.10 in June 2020 which would have broken Covid regulations.
The cabinet secretary has been sent copies of previously unseen messages which suggest the Boris Johnson’s wife held a law-breaking gathering in the Downing Street flat .
A letter sent by a No.10 aide, seen byThe Times, suggests Ms Johnson was in the flat with two friends on the evening of her husband’s birthday and that the prime minister joined her.
At the time, two or more people from different households could not meet indoors except for work purposes.
Sue Gray's investigation looked into 16 events on 12 dates in 2020 and 2021, while Covid-19 restrictions set by the government were in effect, but not this event.
The messages were sent just hours after the PM attended a gathering in the cabinet room for his birthday – for which the Met Police fined him.
They show a Downing Street aide - who claims they were asked to organise the event - telling the PM’s wife that her husband was on his way up to the flat and Ms Johnson responding that she was up there with an unspecified number of male friends.
It is the second party that Johnson’s wife is alleged to have hosted in the flat during the pandemic — no fines were handed out for the other event, the so-called Abba party on November 13, 2020. Gray investigated the Abba gathering but said her enquiries were interrupted by the police inquiries and she had decided it was not worth continuing them afterwards.
An aide sent the letter to Case, according to The Times, having told the Gray inquiry about the messages in January.
The aide told Case they had been willing to come into the Cabinet Office to show the messages to Partygate inquiry officials in person and had agreed to also supply them to the Met’s investigation as well, but Gray’s team had failed to respond.
Two weeks ago, when the Met inquiry had finished, the aide offered again to show the texts to Gray’s team to no avail, according to the newspaper.
The aide wrote to Case offering to share the messages with him after Gray’s report was published on Wednesday.
CSW understands that the Gray inquiry was aware of the aide's claims to have been asked to organise the event, and that these comments were reflected in the final report. However, the Cabinet Office denied that the aide offered to bring the messages into the Cabinet Office so that the investigation team could read them.
A spokesman said the aide had declined to provide the investigators with the messages and had indicated that they would provide them to the Met police instead.
The Cabinet Office said the individual only offered to share the texts after the Met police had concluded its investigation.
In the letter, the aide said they decided to come forward after reading reports questioning the “integrity” of the two investigations, “particularly in relation to an alleged event in the prime minister’s flat on November 13, 2020”.
A spokesman for the Ms Johnson told The Times that Gray was aware of the messages and staff had been “given ample opportunity to present evidence including these messages and all relevant information was passed to the Metropolitan Police for investigation”.