Boris Johnson has overhauled his Downing Street operation following the conclusion of a four-month Metropolitan Police inquiry into lockdown-busting parties at the top of Government during the pandemic.

Scotland Yard’s Operation Hillman was closed on Thursday with a total of 126 fixed penalties handed out to 83 people, although it was confirmed the Prime Minister would not be punished further than the £50 fine he received in April for attending his own birthday bash in June 2020 when indoor mixing was banned.

Mr Johnson’s No 10 shake-up will involve creating a streamlined team of officials working for the Prime Minister under the leadership of his permanent secretary.

It comes ahead of the publication of senior civil servant Sue Gray’s separate report into coronavirus lockdown gatherings in Downing Street and Whitehall, expected next week.A source close to Ms Gray’s investigation told the PA news agency the report could include naming senior figures involved in a “factual context” when explaining what occurred during the events.

However, she will respect the convention of not naming junior civil servants in the final document, which is still being finalised.

The Metropolitan Police declined to identify anyone in its £460,000 investigation.

Ms Gray’s interim report published in January said there were “failures of leadership and judgment” that allowed rule-breaking gatherings to take place in No 10, something the full briefing is expected to expand upon.

The Prime Minister used Thursday’s announcement by the Metropolitan Police about the conclusion of its own probe to push through reforms to his operation amid repeated criticisms of a culture in Downing Street that allowed the Covid law breaches to take place.The PM’s bid to restore order to Downing Street’s operation saw the Government announce changes that will “enhance the support that is offered to the Prime Minister and to the Cabinet”.

It will see the current set-up in No 10 and the Cabinet Office split into two separate groups, according to officials.

The existing No 10 operation, alongside teams in the Cabinet Office supporting Mr Johnson and his top table of ministers, will be placed in a group led by Samantha Jones, the No 10 permanent secretary who was brought in from the NHS in February.

A UK Government spokesman said: “As we set out earlier in the year, steps are being taken to further strengthen the operation of both No 10 and the Cabinet Office so they are best placed to deliver for the public now and in the future.

“Work to deliver these plans is ongoing.”

Northern Ireland minister Conor Burns, a close ally of Mr Johnson, said the Prime Minister would make a statement to the Commons after Ms Gray has published her report but that he wanted to shift the attention onto priorities such as dealing with the cost of living crisis.

Sir Iain Duncan Smith said the PM 'lost control' of No 10Sir Iain Duncan Smith said the PM ‘lost control’ of No 10 (UK Parliament/Jessica Taylor)

Scotland Yard said it had issued 126 fixed-penalty notices (FPNs) to 83 people who attended events in Downing Street and across Whitehall spanning eight separate days.

The probe saw a team of 12 detectives examine 345 documents, including emails, door logs, diary entries, witness statements and 204 questionnaires.

They also examined 510 photographs and CCTV images.

Officers spared Mr Johnson a second fine, with a report in The Mirror suggesting the Conservative Party leader had been told he was only investigated for two events despite having said to have attended at least six of the gatherings being probed.

The newspaper said the police focused on events where there was photographic evidence of his attendance, namely the birthday party he was fined for and a separate so-called “Abba” party in his Downing Street flat on November 13 2020, the night his former de facto chief-of-staff Dominic Cummings quit.

The Met said it would not be commenting when the suggestion was put to them by PA.

Carrie Johnson is understood to have been told by police she would not be handed a second fineCarrie Johnson is understood to have been told by police she would not be handed a second fine (Stefan Rousseau/PA)

According to the Mirror, Mr Johnson’s wife Carrie told police the gathering in the flat with political aide friends was a strategy meeting, while the Prime Minister claimed he was interviewing one of his wife’s friends, a Government adviser, for a new job.

Mrs Johnson and Chancellor Rishi Sunak were fined during the police investigation for attending the Prime Minister’s Cabinet room birthday celebrations.

But Mr Johnson’s wife was understood to have been told by police she would not face any further action, while Mr Sunak has not received another fine.

Cabinet Secretary Simon Case avoided being slapped with an FPN entirely.

Former Tory leader Sir Iain Duncan Smith said Mr Johnson “lost control of what was happening in Downing Street” during the pandemic after an “awful lot of civil servants” had been “caught up” in the Met investigation.

He told BBC Radio 4’s PM programme: “They blurred the line very distinctly about what was work and what was not work, and they shouldn’t have done it and they have been fined, a large number of them, and that is quite right.”