It comes as over the weekend, it emerged that security pass logs which record all of the comings-and-goings at Downing Street have also been looked at.
It is also understood that Martin Reynolds, the Prime Minister’s principal private secretary, who organised the May 20 2020 garden party attended by Mr Johnson despite alleged warnings from two senior members of staff, has helped Ms Gray extensively with her report.
The Sunday Times reported that there are concerns Mr Reynolds has told Ms Gray he checked with Mr Johnson whether to proceed, or can point to a message he sent to Mr Johnson, with one of his colleagues telling the newspaper that “Martin doesn’t have much to lose”.
Mr Johnson has denied that he was told the gathering would break the rules.
The Prime Minister said earlier this month: “I carry full responsibility for what took place but nobody told me. I’m absolutely categorical, nobody said to me this is an event that is against the rules.”
Alleged parties above No 11 also being looked at
If any proof is found that concerns were raised with Mr Johnson about the gathering, he may point to the fact that his denial did not explicitly rule that out. What would be harder to get around would be if the warning did raise the question of rule breaking.
Also drawing Mr Johnson closer to allegations of potential breaches of Covid laws, The Sunday Times claimed that Ms Gray has expanded her inquiry to include alleged parties in the flat that he shares above Number 11 Downing Street with his wife, Carrie, and their family.
It has been alleged that two of Mrs Johnson’s close friends, Henry Newman and Josh Grimstone, who at the time were advisers to Michael Gove in the Cabinet Office, visited the private flat on numerous occasions during lockdown. However, it has been stated that it was for work reasons.
In further bad news for the Prime Minister, Ms Gray could also be set to receive fresh information this week from Dominic Cummings, his former chief of staff, who is expected to speak to her on Monday as part of the report.
He has previously made explosive claims that he and other eyewitnesses were prepared to swear under oath that the Prime Minister had “lied to Parliament about parties” at Downing Street.
With at least 40 officials set to be potentially named in Ms Gray’s report, Mr Johnson is expected to cull a number of his senior team once it has been published in a bid to put the crisis behind him.
These include Dan Rosenfield, the long-time civil servant who became Mr Johnson’s chief of staff only a year ago, Mr Reynolds, and Jack Doyle, the Number 10 director of communications.
Simon Case, the Cabinet Secretary, could also be moved from his post. He was initially charged with investigating allegations of lockdown-busting parties before claims emerged that a potentially rule-breaching event had taken place in his office.
That event was allegedly marked in diaries as “Christmas party”.
Report ‘may not be published in full’
Mr Johnson’s diary is managed by duty clerks and any unplanned events that he attends are often added retrospectively in order to ensure that all “his time is accounted for”.
However, a Whitehall source said the fact that events are often diarised afterwards can make things “tricky” to differentiate between what was planned and what was spontaneous.
A Whitehall source familiar with Ms Gray’s investigation said: “It looks like she’s trying to look at what people have told her and then see what people’s movements are, at what time and which part of the building, what things are being called in diary entries.”
They added that Ms Gray will look at Mr Johnson’s diary “because if he’s given her evidence, she wants to look at something that verifies what he’s saying”.
Meanwhile, amid speculation over how daming the findings may be, Dominic Raab has suggested that Ms Gray’s report may not be published in full.
Although the Deputy Prime Minister said there would be “full transparency”, he refused to confirm that the probe’s findings would be published in its entirety.
Asked if the public will be permitted to see the report in totality, Mr Raab told the BBC’s Sunday Morning programme: “The process for it will be for the Prime Minister to decide. I think the substance of the findings, there will be full transparency, and indeed he has said he will come back to the House of Commons and make a statement so there will be full scrutiny.”
When pressed on whether the report will be published in full, Mr Raab said: “I’m not quite sure the shape and form it will come, but the PM has been clear there will be full transparency around this so that people can see.”
Mr Raab insisted Tory MPs were rallying behind Mr Johnson, although he acknowledged the Prime Minister would have to resign if he was found to have misled Parliament.
“The code of conduct for ministers is very clear that if you mislead Parliament it is a resigning matter,” he told the BBC’s programme.
Last week, Tory MPs raised concerns that Ms Gray’s report could be redacted, prompting calls for all senior figures referenced in the inquiry to be named. However, Number 10 has previously insisted that the report will be published in full.
Angela Rayner, Labour’s deputy leader, stressed that “all accompanying evidence” must be disclosed after Ms Gray presents her report to the prime minister.
She said: “Boris Johnson cannot be allowed to cover up or obscure any of the truth when he has insisted on a hugely protracted internal probe to tell him which parties he attended and what happened in his own home.”