They said that by confirming investigations are under way, but without giving any further detail, it leads to individuals’ reputations being unfairly tarnished.

“The commission should be saying at least when the bet was made. It might be something Laura had no influence over – like betting a fiver on a Tory majority six months ago.”

The ally went on to say that it is highly unlikely that Mr Lee would have known that Mr Sunak was planning to call a summer election.

They added: “Tony [Lee] has been totally cut out – Downing Street runs everything. He has an impressive sounding title but he wouldn’t have known about the snap election.”

In a statement, Ms Saunders’ solicitor said that she would be cooperating with the watchdog’s investigation.

The statement added: “It is inappropriate to conduct any investigation of this kind via the media, and doing so risks jeopardising the work of the Gambling Commission and the integrity of its investigation.”

A Conservative Party spokesman said: “We have been contacted by the Gambling Commission about a small number of individuals.

“As the commission is an independent body, it wouldn’t be proper to comment further until any process is concluded.”

A commission spokesman said: “The Gambling Commission 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.

“This is an ongoing investigation and the commission cannot provide any further details at this time. 

“We are not confirming or denying the identity of any individuals involved in this investigation.”