Liam Booth-Smith spoke to regulator after revelations about betting by those close to PM on date of election

• UK election live – latest updates

Rishi Sunak’s most senior adviser has been interviewed as a witness by officials at the Gambling Commission as part of its investigation into widespread betting by Westminster figures on the date and outcome of the general election.

Liam Booth-Smith, the prime minister’s chief of staff, spoke to the regulator last week after a series of revelations about betting by people close to the prime minister on the date of the election.