Pressure is mounting on the prime minister over Downing Street lockdown parties ahead of the release of the Sue Gray report into partygate.

Number 10 is expecting to receive the inquiry’s final report on Wednesday. It is anticipated to be more in-depth than the Met Police investigation that concluded last week – and will include names of rule breakers.

Criticism over the Met’s investigation has ramped up after photos emerged on Monday of Boris Johnson giving a toast to colleagues in Downing Street allegedly on 13 November 2020, during England’s second national lockdown.

Police decided to not fine the PM over the event but at least one other person was.

Politics hub: Live updates ahead of Sue Gray report publication

London Mayor Sadiq Khan was among those calling for the Met to explain why Mr Johnson only received a single fine for breaching lockdown rules with his 56th birthday gathering.

The police watchdog confirmed on Tuesday it had received a complaint from the Lib Dems over the Met’s investigation, which urges them to establish how Met detectives reached a conclusion to not fine the PM for events on 13 November 2020.

Former Met chief superintendent Dal Babu told Sky News he was “flabbergasted” the PM was not fined for the event.

The Met’s perceived failure by some has further piled pressure on the Sue Gray report to reveal more details.

MPs, including some Conservatives, have accused Mr Johnson of misleading parliament after he denied being at the 13 November party following a direct question about his attendance on 8 December 2021.

Veteran Conservative MP Roger Gale said that was a “resignation issue”.

Cost of living measures being brought forward

In what some are seeing as an attempt to reduce the sting from the Sue Gray inquiry, the chancellor is understood to be introducing financial help for the cost of living crisis on Thursday – bringing forward a June announcement.

Another picture, obtained by The Mirror, emerged on Tuesday evening showing a man standing at a table in Downing Street with nine bottles of wine and prosecco as well as doughnuts and miniature cakes.

It is believed the gathering was a leaving do for the PM’s then-official spokesman James Slack on 17 November 2020, during the second national lockdown.

Thirty to 40 staff are understood to have attended and the event was not investigated by police.

Mr Johnson is understood to have encouraged staff to “let off some steam” as they worked hard during the pandemic.

‘Regular rule breaking’

Three Downing Street insiders told the BBC they witnessed regular rule-breaking during coronavirus restrictions, with weekly invitations for press office drinks listed as “wine-time Friday”.

Party debris was left overnight for employees arriving the next day, the insiders said as they told of crowded gatherings where people sat on each other’s laps.

One said they felt they had the permission of Mr Johnson as he was not telling them to break up scenes and was “grabbing a glass for himself”.

Security guards are also said to have had to send an email around Downing Street telling people to cease having events.

Downing Street has said it handed all photos and evidence to the Met Police and the Sue Gray inquiry.

The PM’s spokesman said he could not “get into commenting on claims put forward given Sue Gray’s report has not been published yet”.

“You will hear from the prime minister once that has happened, so I am limited in what I can say,” he added.