Dominic Cummings claims fearful Downing Street staff are keeping evidence from Sue Gray inquiry

Dominic Cummings has claimed evidence is being kept from Sue Gray’s investigation into drinks parties at No 10 and Whitehall because staff fear it will be seen by Boris Johnson.

The former Downing Street adviser also suggested that the fear meant that further evidence – including photographs – will keep leaking after the top civil servant publishes her report.

“I know others are very worried about handing things to the Cabinet Office because they know the PM will see everything SG [Sue Gray] collects,” Mr Cummings said in his latest blog post.

It followsThe Independent’s exclusive report that officials at No 10 have held back information from Ms Gray’s investigation into the partygate scandal due to a “culture of fear” surrounding the probe.

Three sources said they had not divulged messages and pictures on their phones after a senior member of staff told them to remove anything which could be damaging following the first party revelations.

Mr Cummings wrote on Monday that fear among staff “inevitably means that evidence, including photos, is not given to her and instead will keep leaking after her report”. He added: “To stress, this is a consequence of beliefs about the PM’s integrity, not SG’s.”

Urging Conservative MPs to commit to ousting Mr Johnson from office, he added: “Other damaging stories will come out until he is gone.”

In a clear warning to Tory backbenchers, Mr Cummings also tweeted: “Expect the parties story to roll on after report cos photos etc will not be given to the Cabinet Office. MPs must scrap [Mr Johnson] if they want the nightmare to end.”

Mr Cummings also made clear that he was not meeting Ms Gray on Monday as reported, but was submitting evidence to her investigation in writing.

The former No 10 strategist claimed that if he spoke to the investigating civil servant in person, it would give the prime minister and No 10 the chance to spin his account of events.

He wrote on his blog: “When SG [Sue Gray] asked to speak to me I emailed to the effect: if we speak, the PM will invent nonsense and spin it to the media, and you and I will both have problems; let’s keep everything in writing, therefore he cannot invent things I’ve supposedly said to you, there is only a written record, this makes both our lives easier.

The PM’s former adviser added: “She agreed. So I have answered questions in writing and will answer further questions in writing if she wants. But I will not speak and therefore provide the PM with more chances to lie and confuse everybody.”

Ms Gray is reportedly set to report back to the prime minister later this week before the findings are made public.

Mr Johnson’s official spokesperson rejected Mr Cummings’ claim, saying: “From the start, all staff have been encouraged to cooperate fully with the investigation team and their work, and that’s been reiterated on a number of occasions throughout the process.

“More broadly the investigators aren’t sharing with No 10 – and indeed the prime minister - any updates about who they are or are not speaking to and what facts they’re ascertaining.”

He added: “The prime minister will be presented with the report once their work is done and that will be the first he has seen of the facts that they have gathered.”

The Cabinet Office official has been asked to investigate allegations about gatherings held in 2020 and 2021 while Covid restrictions were in place, including a “bring your own booze” event at No 10 in May 2020.

Labour’s deputy leader Angela Rayner has said the report “must be published in its entirety with all accompanying evidence”.

Mr Cummings said he would be doing a question-and-answer session on his blog after the report is released.