A police officer working as part of the prime minister’s close protection team has been arrested over alleged bets about the timing of the general election, the BBC has learned.
The officer was initially suspended by the Metropolitan Police and then arrested on suspicion of misconduct in public office.
Mr Sunak announced 4 July as the date of the general election on 22 May, taking much of Westminster by surprise.
The Gambling Commission is looking into alleged betting offences connected to the date of the election.
The Met was contacted by the watchdog last Friday, which informed the force that it was investigating alleged bets made by a police constable from the Met’s Royalty and Specialist Protection Command.
The Met told the BBC: “The matter was immediately referred to officers in the Met’s Directorate of Professional Standards, who opened an investigation, and the officer was also removed from operational duties.”
The officer was arrested on Monday, then taken into custody and bailed pending further enquiries.
The matter has also been referred to the Independent Office for Police Conduct.
The Met Police said the Gambling Commission continues to lead the investigation into the alleged betting offences, and “our investigation is running in parallel to that”.
A spokesperson for the Gambling Commission said it “regulates gambling in the interests of consumers and the wider public.”
“Currently the commission is investigating the possibility of offences concerning the date of the election,” the statement said.
Responding to the arrest, Liberal Democrat deputy leader Daisy Cooper said: “Rishi Sunak must call a Cabinet Office inquiry into what is shaping up to be yet another scandal at the heart of government.
“This stinks of yet more sleaze and answers are needed.
“An inquiry is needed to understand who knew what and when.”
Separately, one of Rishi Sunak’s closest aides, Craig Williams, was alleged to have placed a £100 bet on a July polling day three days before the PM named the date as 4 July.
Mr Williams, who was the Tory MP for Montgomery until the election was called and is standing again in the new constituency of Montgomeryshire and Glyndwr, previously said he had made a “huge error of judgement” but refused to say whether he placed a bet on the basis of insider information.
You can see a full list of candidates for the Montgomeryshire and Glyndwr constituency here.