A senior Conservative has been accused of placing an £8,000 bet that he would lose his seat at the election, as the gambling scandal continues to dominate the campaign.

Sir Philip Davies, who is married to Cabinet minister Esther McVey, is defending a 6,242 majority in Shipley, West Yorkshire.

The alleged bet was first reported by The Sun. When approached by the paper, Sir Philip said the sum involved was “nobody’s business” and that he “fully expected to lose the seat”, but insisted he had done nothing illegal.

He added: “I hope to win. I’m busting a gut to win. I expect to lose. In the 2005 election, I busted a gut to win. I expected to lose.”

At least five Conservatives are being investigated by the Gambling Commission as part of its inquiry into wagers on the timing of the 4 July election.

The Met Police will lead on investigating a “small number of cases” related to the Westminster gambling row to “assess whether the alleged offending goes beyond Gambling Act offences to include others, such as misconduct in public office”.

A Met Police spokesperson said: “The Met is not taking over the investigation into bets on the timing of the General Election.

“The Gambling Commission will continue to lead the investigation into cases where the alleged offending is limited to breaches of the Gambling Act only.

“Met detectives will lead on investigating a small number of cases to assess whether the alleged offending goes beyond Gambling Act offences to include others, such as misconduct in public office. We will provide further information tomorrow.”

On Tuesday, Russell George, a member of the Welsh Parliament, was told that he was now part of the watchdog’s inquiry.

Mr George said he would co-operate fully with the commission and would not be commenting further, saying it was the official body, “not the media”, to decide any wrongdoing.

“I have stepped back from the shadow cabinet while the investigation is ongoing. I have done this as I do not wish to be an unnecessary distraction to their work,” he said.

Cabinet minister Alister Jack has also admitted placing bets on the election date, although he is not being investigated by the regulator because he staked the money earlier in the year, before the period covered by the watchdog’s probe into the alleged use of inside information.

The Prime Minister has suspended candidates Craig Williams, who is standing in Montgomeryshire and Glyndwr, and Laura Saunders, who is standing in Bristol North West, amid the betting investigation.

Ms Saunders’ husband, Tony Lee, the party’s director of campaigning, and chief data officer, Nick Mason, have stepped back from their duties.

Labour has also been drawn into the row, suspending candidate Kevin Craig after he was investigated by the regulator for betting on himself to lose his contest in Central Suffolk and North Ipswich.

Moreover, one of Rishi Sunak’s police protection officers was arrested on suspicion of misconduct in public office in relation to bets placed on the timing of the general election and is on restricted duties. Five other Met officers were later identified in the commission’s probe.

Amid the growing scandal, Labour leader Sir Keir Starmer said the rules were not the problem, politicians using inside knowledge were.

During the BBC election debate on Wednesday night, both party leaders were quizzed on the scandal. Mr Sunak said “that given the seriousness and the sensitivity of the matters at hand that they were dealt with properly, and that’s what I’ve done”.

Previously, Mr Sunak has said he “will not hesitate to act” against party officials if they are found to have cheated by placing bets on the timing of the election.

Earlier on Wednesday, Home Secretary James Cleverly admitted the deepening Westminster betting row “distracts the conversation away from the really important issues”, but declined to say whether rules around gambling on politics should be changed.

The Home Secretary said he was “furious that people who should have been motivated exclusively by public service” wagered on the election, but insisted on awaiting the outcome of Gambling Commission probe before making any decisions on rule changes.

During a campaign visit to Nottinghamshire, Mr Cleverly said: “We are furious that people who should have been motivated exclusively by public service have done this. That is why we have taken action internally as a party.

“Of course this distracts the conversation away from the really important issues. I’d much prefer to be talking about the low-tax choice under the Conservatives and the high-tax choice under Labour.”

Additional reporting by PA