Tony Lee, the Conservative director of campaigning, has taken a “leave of absence” while he is investigated over an alleged bet on the date of the election, and his wife, Laura Saunders, an MP candidate, is also facing an inquiry by the gambling watchdog.
Craig Williams, a senior aide to Mr Sunak and an MP candidate, bet £100 on the election date just before it was called and is also under investigation.
Sir Keir Starmer, the Labour leader, has said that Mr Sunak must publicly reveal who in his party had knowledge about the date he was planning to call.
Analysis of betting patterns on Betfair Exchange reveal the unusual flurry of wagers placed on a July date in the hours leading up to the Prime Minister’s announcement.
More bets of over £25 were placed on May 21 than in the entire period leading up to the calling of the election, with 14 of them worth £50 or more.
At just after midday a bet of around £400 was made on the snap summer election, despite the odds of it happening at that point being just 8/1.
At 4pm another wager of £425 was placed, by which time the odds had halved to 4/1.