Prime Minister Rishi Sunak has said he is “disappointed” after his aide Craig Williams bet on a July election.

Mr Williams, who was the PM’s parliamentary private secretary (PPS), is facing an investigation after he “put a flutter on the general election” just days before the 4 July date was announced.

A PPS is a backbench MP who acts as the prime minister’s “eyes and ears” in the Commons.

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He has so far refused to confirm whether he had any inside information when he placed the bet.

Today, Mr Sunak was asked if Mr Williams knew about the July date at the time.

He told reporters in Puglia, where he is attending the G7 summit: “Well, it’s very disappointing news and you would have seen Craig Williams say that it was a huge error of judgement.”

As the Gambling Commission is now conducting an investigation, Mr Sunak said it “wouldn’t be appropriate for me to comment while that’s ongoing”.

Asked two more times, the PM would not budge, saying it “wouldn’t be right for me to comment… given the nature of the inquiry, it is necessarily independent and confidential”.

Liberal Democrat leader Ed Davey was today asked on the campaign trail what he thought.

“I don’t know the details of the case, but if someone knows the outcome of something, it seems to me morally questionable for them to put a bet on it if they know the result of that outcome,” he said.

Dyfed-Powys Police, the force in Mr Williams’s constituency, said the event does not “require police involvement” as the Gambling Commission has “the powers to investigate and prosecute under the Gambling Act”.

Mr Williams placed a £100 bet on a July election just days before Mr Sunak named the date as 4 July, The Guardian first reported.

He was said to have placed the bet at a Ladbrokes in his constituency and based on odds at the time he would have won £500.

Mr Williams today told the BBC he “apologises” and yesterday said he “should have thought through how it looks”.

He is standing in this election in Montgomeryshire & Glyndwr in next month’s election, alongside Jeremy Brignell-Thorp for the Green Party, Oliver Lewis for Reform UK, Glyn Preston for the Liberal Democrats, Elwyn Vaughan for Plaid Cymru and Steve Witherden for Labour.