The investigation into whether Sir Keir Starmer broke coronavirus rules cost the public £101,000, police have said.
Durham Police launched an inquiry after the Labour leader was filmed drinking beer in an MP's office in April 2021 when Covid restrictions were in place.
Responding to a Freedom of Information (FOI) request, the force revealed nine officers spent about 3,200 hours on the so-called Beergate investigation.
Sir Keir and his team were cleared of any wrongdoing in July.
At the Durham gathering on 30 April, which was in the run-up to the Hartlepool by-election, people drank beer and ate curry in the constituency office of Labour City of Durham MP Mary Foy.
Social distancing rules – including a ban on indoor mixing between households – were in place at the time.
However, Labour had argued the food was consumed between work events, meaning the gathering was within the rules.
This video can not be played
Footage shows Sir Keir Starmer drinking beer with colleagues in Durham on 30 April 2021
They had been initially cleared by police in February of breaking any laws but officers reopened the investigation into the event in May after receiving "significant new information".
Following the conclusion of that inquiry, police said they would not be issuing any fines and no further action would be taken.
The FOI revealed a detective superintendent, a detective inspector, a detective sergeant and six detective constables from the Major Crime Team worked on the case, alongside two members of police staff.
The request was submitted by National World, which first reported the story.
This video can not be played
WATCH: Keir Starmer's statement when he was cleared in July
The force's reply said: "After careful consideration and performing a public interest test, I [the decision maker] have deemed that the public interest lies in the disclosure of this information, as it relates to the spending of public money, and also the resources Durham Constabulary had to utilise to conduct this investigation."
It said the money came from the "general policing budget" and that the Major Crime Team "continued to operate normally and conduct other investigations".
Earlier this year, then-Prime Minister Boris Johnson was fined for attending a birthday party during lockdown in June 2020.
Follow BBC North East & Cumbria on Twitter, Facebook and Instagram. Send your story ideas to northeastandcumbria@bbc.co.uk.
Starmer says he hated being investigated by police
Starmer cleared by police over Durham event
Keir Starmer's Durham drink – what were the rules?
Starmer: Police not in touch over Covid beer
Durham Police
FEELING GREAT: By doing the basics every day you’ll help make a difference to your health
Looking for a job over Christmas? These are some of the positions available in and around Sunderland and the North East
Hour-by-hour North East forecast on Thursday and Friday as changeable weather to continue
Dogs, sports cars and State Troopers: 15 pictures as car show draws big crowds
15 pictures from Seaton Carew as dogs, kids and families enjoy car show
See inside new Japanese restaurant Butakun
Putin vows to 'stabilise' annexed Ukrainian regions
Iran schoolgirls heckle paramilitary speaker
Rivals Biden and DeSantis project unity over storm
Seven pivotal moments that made Putin
Why I robbed a bank to get my own money. Video
The terrors of Kenya’s school arson epidemic
Will UK royals follow the Danish downsizing?
The generations of Iranian women fighting for freedom. Video
Space, the unseen frontier in the war in Ukraine
Fat Bear Week is back and bigger than ever
Ukraine designers fight back at Paris Fashion Week
Can India be China’s ‘plus one’ to the world?
Why Gen Z are drinking less
The books too powerful to read
The African city Europeans tried to erase
© 2022 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.