Sue Grays's full report into Downing Street parties in Whitehall during the coronavirus lockdown is expected to be heavily critical of the culture in No 10.
There were repeated violations of Covid restrictions - and the senior civil servant’s report is expected to include further damaging details, including the names of some of those who attended gatherings. Those to be named were written to ahead of its publication, allowing them to have a chance to respond before it was finalised.
The full report could be published on Wednesday, however, the BBC said on Tuesday evening the senior civil servant will hand in her completed report that day. The decision over its publication date will then be left up to No 10 with a Downing Street press conference expected to be held after her findings are made public.
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Prime Minister Boris Johnson is scheduled to address the 1922 Committee of backbench Tories on Wednesday. He is also due to address the Commons.
According to an earlier, shortened version published in January, Ms Gray’s investigation analysed events from May 15 2020 to April 16 2021. The full publication into the parties was sidelined as the Metropolitan Police conducted its own partygate probe, dubbed Operation Hillman.
The force concluded its investigation on May 19, with 126 fines being issued in total to 83 people. Mr Johnson received one for an event held on his 56th birthday and was told he would face no further action over other gatherings covered by the inquiry.
Earlier this week, two new photographs apparently depicting separate gatherings at Downing Street were published. Images obtained by ITV appeared to show Mr Johnson raising a toast and drinking wine at a gathering held to mark the departure of former spin doctor Lee Cain on November 13 2020.
The Mirror meanwhile published a picture showing a man standing at a table with nine bottles of wine and prosecco, which was claimed to have been taken at a gathering to mark the final press briefing Mr Johnson’s former official spokesman James Slack on November 17 2020.
On Tuesday evening, the BBC broadcast a Panorama programme which featured three anonymous individuals describing in detail what they witnessed at regular rule-breaking events during coronavirus restrictions. They said events were "every week", with invitations for press office drinks listed in the diary as "Wine-Time Friday".
On Tuesday, Mayor of London Sadiq Khan wrote to the acting head of the Metropolitan Police Sir Stephen House to explain the force’s decisions over partygate after pictures emerged of Mr Johnson drinking at a gathering for which he was not fined.
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