Allegations about gambling on the election engulfed the Conservative campaign in June after it emerged senior Tory officials and one of Rishi Sunak’s aides had placed bets shortly before the date was announced.
The Gambling Commission launched an investigation into whether this broke laws on “cheating” while the Met opened a separate inquiry into whether other offences had been committed.
One officer, believed to be part of Mr Sunak’s close protection team, was arrested on suspicion of misconduct in public office as part of the investigation while a total of seven officers were alleged to have placed bets.
On Friday, the force announced its criminal investigation had concluded with no action being taken, including against the officer who had been arrested.
The Gambling Commission investigation remains ongoing and could still result in criminal charges while the Met’s Directorate of Professional Standards is continuing to investigate the seven officers alleged to have placed bets on the election date.
In a statement, the Metropolitan Police said the “high bar” for proving misconduct in public office had not been met, following advice from the Crown Prosecution Service.
Detective Superintendent Katherine Goodwin said: “These allegations caused a significant dent in public confidence during the election campaign and it was right that they were investigated to explore all possible offences.
“While our involvement in the criminal investigation now ceases, it’s important that is not misinterpreted as an all-clear for those whose cases were looked at.
“There are still Gambling Act offences to consider and it is appropriate that they are taken forward by investigators from the Gambling Commission who have particular expertise in this field.”
Gambling Commission chief executive Andrew Rhodes said his organisation had already interviewed “several suspects” under caution and continued to speak to witnesses and gather documentary and electronic evidence.
He said: “We clearly appreciate the level of public interest there is in this investigation but in order to protect the integrity of the investigation and to ensure a fair and just outcome, we are unable to comment further at this time, including the name of any person who may be under suspicion, or the total number of suspects.”
The gambling scandal was triggered by revelations Mr Sunak’s former parliamentary private secretary Craig Williams admitted having a “flutter” on the election date shortly before it was announced.
The Conservatives eventually withdrew support for Mr Williams as their candidate for Montgomeryshire and Glyndwr, along with Bristol North West candidate Laura Saunders, who was also alleged to have placed a bet.
Ms Saunders’ husband, Tony Lee, the Conservative Party’s director of campaigning, and Tory chief data officer Nick Mason took leaves of absence during the campaign after being implicated in the scandal, while Senedd member Russell George stepped back from the shadow cabinet in the Welsh Parliament after being placed under investigation.