LONDON, July 2 -- The rooms Craig Williams entered in the weeks before Britain's 2024 general election were not ordinary. He was parliamentary private secretary to the Prime Minister - Rishi Sunak's political shadow - sitting in on Downing Street planning sessions as the government deliberated over the single most consequential question of that political year: when to call the election.

He left those meetings and placed bets.

On June 29, a judge at Southwark Crown Court accepted Williams' guilty plea to a charge of cheating under section 42(1)(a) of the Gambling Act 2005. He had used insider knowledge accumulated during his most privileged access as a senior political aide to wager on the timing of the poll. Amy Hind, 35, who had worked...