By Helen Catt, Political correspondent • Adam Durbin, BBC News
A fourth senior Conservative is being looked into by the Gambling Commission over bets allegedly placed on the date of the general election.
The Sunday Times reported that the party’s chief data officer Nick Mason allegedly placed dozens of bets, which the paper says could have generated winnings of thousands of pounds.
A spokesman for Mr Mason told the BBC that it would not be appropriate to comment during an investigation but he denied wrongdoing.
Mr Mason has now taken a leave of absence from his Tory party role, 11 days from election day on 4 July.
The Conservative Party said it was “not permitted to discuss any matters related” to any Gambling Commission investigation.
The BBC has previously reported that two Conservative election candidates and another party official are also being investigated.
Both Laura Saunders and Craig Williams have confirmed they were being investigated by the Gambling Commission.
Ms Saunders, the party’s candidate in Bristol North West, has worked for the Tories since 2015.
Ms Saunders’s partner is the Conservative director of campaigning Tony Lee, who is also being looked at over an alleged bet. He has taken a leave of absence from his job.
The allegations of gambling on the election date first emerged against one of Prime Minister Rishi Sunak’s closest aides, Mr Williams, who reportedly placed a £100 bet on a July polling day three days before the date was named.
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 apologised and said he made a “huge error of judgement”.
When asked by the BBC, he refused to say whether he placed a bet on the basis of inside information.
Speaking about the allegations on the BBC’s Sunday with Laura Kuenssberg programme, Home Secretary James Cleverly said the Gambling Commission were investigating and it was “right and proper that we let them do their job”.
Asked if any ministers had placed a bet on the timing of the election, Mr Cleverly said: “Not to my knowledge.”
Following the latest allegation, a Conservative spokesman said: “As instructed by the Gambling Commission, we are not permitted to discuss any matters related to any investigation with the subject or any other persons.”
Last week, Mr Sunak said he had been “incredibly angry” to learn about the allegations, promising to “boot out” anyone found to have broken gambling laws from the Conservative Party.
Mr Sunak announced 4 July as the date of the general election on 22 May, taking much of Westminster by surprise.
If someone uses confidential information to gain an unfair advantage when betting, this could be a criminal offence under section 42 of the Gambling Act.
A spokesperson for the Gambling Commission confirmed to the BBC it is “investigating the possibility of offences concerning the date of the election”.
The Commission also said it could not provide any further details about the investigation or who was being looked into as it is an ongoing process.
“We are not confirming or denying the identity of any individuals involved in this investigation,” it said.
Both Labour and the Liberal Democrats called for Mr Sunak to suspend those under investigation.
Labour’s shadow education secretary Bridget Phillipson described the allegations as “pretty shocking” and said there would be “genuine disgust” amongst voters.
Liberal Democrat deputy leader Daisy Cooper said the PM should launch a Cabinet Office inquiry into the reports, which she described as an “all-out scandal at the heart of the Conservative Party”.
“People are sick and tired of this sleaze. Day by day, hour by hour, the Conservative government mire themselves in more of it”, she said.
Housing Secretary Michael Gove has condemned the latest reports, and likened the controversy to Partygate during the Covid-19 crisis.
“It looks like one rule for them and one rule for us,” the Tory cabinet minister, who is not standing again at the election, told the Sunday Times.
It has also emerged that a police officer working as part of the prime minister’s close protection team had been arrested following an allegation of bets on the timing of the election.
The officer was initially suspended by the Metropolitan Police and then arrested on suspicion of misconduct in public office.
The individual has been bailed pending further inquiries.
The Met was contacted by the Gambling Commission last Friday. It informed the force that it was investigating alleged bets made by a police constable from the Met’s Royalty and Specialist Protection Command.
You can find a full list of candidates for the Bristol North West and Montgomeryshire and Glyndwr constituencies on the BBC News website.