Sunak refuses to say whether he told gambling row aide the election date

So far five Conservatives are known to have been caught up in the Gambling Commission inquiry, including Mr Sunak’s former parliamentary aide, Craig Williams.

The Prime Minister has withdrawn Tory support for Mr Williams in his bid to be returned as MP for the Montgomeryshire and Glyndwr seat, after he admitted having a “flutter” on the election date.

During a campaign visit in Derbyshire, Mr Sunak was repeatedly asked whether he had confided in Mr Williams ahead of his surprise announcement of a summer election.

Speaking to broadcasters, the Prime Minister said: “I’ve been clear about this. I’m furious to have learnt about these allegations.

“We’ve initiated independent inquiries of our own, because I don’t have access to the Gambling Commission’s detail.

“You’ll recognise that while there are ongoing independent investigations, it’s just not right for me to say anything more about that.”

The Prime Minister was told he could not prejudice the investigation and that he could absolutely answer the question of whether or not he told the parliamentary candidate about the date.

He replied: “No, it’s absolutely not right when there are ongoing independent investigations that those are compromised in any way shape or form.”

Mr Sunak was told he could not “compromise” the investigations by clarifying whether or not he had told Mr Williams the date of the election, to which he said: “They are rightly confidential and it’s important that they stay that way.”

He also told reporters he was “not aware” of any parliamentary candidates or Conservative officials being investigated beyond those already in the public domain.

As well as Mr Williams, the Tories have withdrawn support from Bristol North West candidate Laura Saunders.

Ms Saunders’ husband, Tony Lee, the Conservative Party’s director of campaigning, has taken a leave of absence, as has Tory chief data officer Nick Mason, while Senedd member Russell George stepped back from the shadow cabinet in the Welsh Parliament after being placed under investigation.

But BBC reports have suggested as many as 15 Tory candidates and officials could be under investigation.

Meanwhile, Scotland Yard said at least seven of its officers were being investigated over bets on the timing of the election.

The Met had previously indicated that six officers were under investigation, including one of Mr Sunak’s protection team, who was arrested on suspicion of misconduct in public office.

Under the joint approach from the Met and the betting regulator, the Gambling Commission will look at alleged offences of cheating, contrary to Section 42 of the Gambling Act.

Those are likely to make up the majority of the cases being examined.

The Met will look at cases with specific features which could result in further offences, such as Misconduct in Public Office, although Scotland Yard suggested that would be a “much smaller” number of cases.

Gambling Commission chief executive Andrew Rhodes said: “We are focused on an investigation into confidential information being used to gain an unfair advantage when betting on the date of the General Election.

“Our enforcement team has made rapid progress so far and will continue to work closely with the Metropolitan Police to draw this case to a just conclusion.”

Detective Superintendent Katherine Goodwin, who is leading the Met investigation, said: “We have agreed a joint approach with the Gambling Commission, who are the appropriate authority to investigate the majority of these allegations.

“There will, however, be a small number of cases where a broader criminal investigation by the police is required.”

Sir Philip Davies, the husband of Cabinet Office minister Esther McVey, became the latest Tory candidate to be accused of gambling on the election.

He reportedly bet £8,000 against himself holding his marginal Shipley constituency, according to The Sun.

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

Speaking to broadcasters during a campaign visit to Staffordshire, Labour leader Sir Keir Starmer said he was not aware of any other Labour candidates having bet against themselves.

“No. You saw my action,” he said, on the move to suspend Mr Craig almost immediately after the Gambling Commission confirmed it was looking into his wager.

“I think this latest development highlights one, how serious this is, two, that the Prime Minister should have acted swiftly at the beginning and shown leadership rather than being bullied into taking action, and three, the wider choice now at the election between carrying on with this sort of behaviour, bending the rules and breaking the rules, disregarding the rules.

“We’ve got to stop that and usher in a reset.”