Fifteen people, including former Tory MP Craig Williams, have appeared in court charged with betting offences linked to the timing of last year's general election.
It follows an investigation by the Gambling Commission into alleged betting on the date of the election.
Appearing at Westminster Magistrates Court on Friday, Williams was among three defendants who gave no indication of a plea at this stage.
Twelve others, including Russell George, a former Conservative now independent member of the Welsh Senedd, indicated they would deny the charges.
The defendants will appear again at Southwark Crown Court on July 11.
On 22 May 2024, Rishi Sunak announced the general election would be held on 4 July that year, overturning previous expectations of an autumn poll.
Prosecuting on behalf of the Gambling Commission, Sam Stein KC said Sunak was among those to have given a witness statement in the case.
Mr Stein told the court the commission's investigation was launched into "politicians and employees of the Conservative Party, and a former police officer... who had placed bets on the date of the 2024 general election with the benefit of confidential or insider information as to when that date might be".
"The prosecution says that placing bets with inside information is a criminal offence, namely cheating," he added.
Before the election was called, Williams was the MP for Montgomeryshire and a parliamentary aide to Sunak.
He was previously MP for Cardiff North between 2015 and 2017, before he lost his seat to Labour in the election that year.
Along with Williams, former police officer Jeremy Hunt, 55, of Horne in Surrey, and Jacob Willmer, 39, from Richmond, west London, did not indicate a plea.
Along with George, those indicating a not guilty plea included Laura Saunders, the former Conservative parliamentary candidate in Bristol North West, and her partner Anthony Lee.
The others indicating they would deny the charges included Simon Chatfield, 51, from Farnham, Surrey, Amy Hind, 34, of Loughton, Essex, Anthony Hind, 36, of Loughton, Essex, Thomas James, 38, Charlotte Lang, 36, Iain Makepeace, 47, from Newcastle Upon Tyne, Nick Mason, 51, Paul Place, 54, from Hammersmith, west London and James Ward, 40, of Leeds.