Ms Gray, the senior civil servant who has produced a report around lockdown breaches committed at Downing Street and Whitehall, is reportedly in discussions about naming senior political and Civil Service figures.
It comes with Scotland Yard facing demands to prevent people being left “in the dark” by explaining why Boris Johnson escaped his Partygate investigation with only one fine.
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The Prime Minister was told he faces no further action when the Metropolitan Police closed its inquiry after issuing 126 fines for lockdown breaches in Downing Street and Whitehall.
But there were calls for clarity after Mr Johnson received just the one fixed penalty notice despite being believed to have been present at multiple rule-breaking events.
Potentially damaging further details, including some names, will be published in Sue Gray’s highly-anticipated report, which sources close to the investigation expect will be published early next week.
Officials impacted by the senior civil servant’s inquiry will be contacted over the weekend and given a chance to respond, before the current draft is finalized for publication.
It was understood Mr Johnson was contacted by the team on Thursday afternoon as they run the “gist” of allegations past those involved.
Former director of public prosecutions Lord Ken Macdonald warned “it’s very difficult for us to disentangle exactly how the police investigation has proceeded and how fair it’s been”.
He told BBC Radio 4’s Today programme: “I think without the police providing an explanation for that, it’s very difficult for us to understand why they came to the conclusions that they did.”
The crossbench peer said it was not known why the Prime Minister was fined for his presence at what was considered one of the less serious events, a gathering for his 56th birthday, but not others.
There has also been no explanation as to why Cabinet Secretary Simon Case, who had to recuse himself from running the inquiry after reports of a Cabinet Office Christmas party surfaced, has not been fined.
“This was a major scandal at the heart of Government, at the heart of the civil service, and we remain very much in the dark about who was involved, who organized the parties, and who was responsible,” Lord Macdonald, who led the Crown Prosecution Service between 2003-08, said.
“Of course the Prime Minister and the head of the civil service are ultimately responsible, but there plainly were other people as well who were involved in this and we simply don’t know who they are, and I think that’s not good enough.”
Closing its investigation on Thursday, Scotland Yard said a total of 83 people had received at least one fine each for attending events over eight separate days.
Deputy prime minister Dominic Raab insisted there would be “transparency” around publishing the Gray report “as soon as possible”.
“And the Prime Minister said he will come to the House of Commons and take questions so that we get that additional tier of transparency and accountability,” Mr Raab told Times Radio.
One source close to the Gray investigation said it could be published as soon as Monday, but it was thought Tuesday or Wednesday were more likely.
When Ms Gray’s team hands over the document depends on the scale of the objections received by those being approached for checks.
The individuals she intends to name will be contacted, but it was understood others who are approached could remain anonymous.
The team is not believed to be showing individuals being contacted for pre-publication checks the detailed allegations, but are giving a flavor of what it contains.
But ultimately its publication is being handled by No 10.
The Metropolitan Police declined to identify anyone in its £460,000 investigation.
A team of 12 detectives examined 345 documents, including emails, door logs, diary entries, witness statements and 204 questionnaires.
They also examined 510 photographs and CCTV images.
Mr Johnson, his wife Carrie Johnson, and Chancellor Rishi Sunak were all fined over a 56th birthday gathering for the Prime Minister in June 2020 when indoor mixing was banned.
But both Johnsons were told by police they face no further action, according to Downing Street, and Mr Sunak has not received an additional fine.
The Met said 28 individuals had received between two and five fines.
George Holan is chief editor at Plainsmen Post and has articles published in many notable publications in the last decade.