George and Fiona Cottrell understood to have been interviewed under caution by Met police

Interviews of Farage aide and his mother believed to be part of investigation into donations to Reform UK before 2024 election

Nigel Farage’s aide George Cottrell and his mother, Fiona Cottrell, have been interviewed under criminal caution by Scotland Yard detectives, the Guardian understands.

The interviews are understood to form part of an ongoing investigation into donations to Reform UK before the general election in July 2024.

Both Cottrell, known as “posh George”, and his mother were invited for interview by detectives from the Metropolitan police’s special inquiry team. They attended voluntarily, the Guardian understands.

Fiona Cottrell, who lives in Worcestershire and once dated King Charles, has not responded to questions from the media about any issues involving her support for the Reform party.

Lawyers acting for George Cottrell, who lives in Montenegro, said he had no comment to make. In a previous letter to the Guardian, the lawyers stated that “his mother’s donations have been entirely her own decision, and are a matter for her”.

They added that suggestions he “has donated impermissibly to Reform UK are unfounded”.

The Met decided to launch a criminal investigation last year after a referral was made by the Electoral Commission.

The investigation is examining “donations made to a political party ahead of the 2024 UK general election” and “alleged offences under section 61 of the Political Parties, Elections and Referendums Act 2000 ” (PPERA), according to a Met statement released on Thursday.

The act is designed to stop the evasion of restrictions on donors to political parties.

It is an offence if a person knowingly enters into, or knowingly does any act in furtherance of, “any arrangement which facilitates or is likely to facilitate, whether by means of any concealment or disguise or otherwise, the making of donations to a registered party by any person or body other than a permissible donor”.

The PPERA also makes it an offence to knowingly give the treasurer of a registered party any information relating to the amount or source of a donation which is false, and “with intent to deceive … withholds … any material information relating to” the source or amount of the donation.

The Guardian understands the Met investigation is expected to take many more months and involves police seeking disclosure and documents from banks and other financial institutions.

The force says it has sought and received early investigative advice from the Crown Prosecution Service.

A criminal caution protects the rights of those being interviewed as well as meaning anything said could be used as evidence.

On Thursday, the Times reported that the police were investigating donations worth £500,000 made to Reform UK by Fiona Cottrell in May 2024.

The Guardian now understands the Met inquiry, which began in February 2025, is broader than that and is looking at other financial issues relating to Reform.

The Guardian revealed this week that a number of financial transactions involving senior figures within the Reform party had been reported to the National Crime Agency by bankers who were concerned it could potentially be laundered money.

It is understood that the origin of the Met investigation was the £1m given to a fundraising vehicle for Reform UK, Britain Means Business, on 10 June 2024 by Fiona Cottrell. Half of this, £500,000, was transferred to Reform UK by 12 June, just weeks before the general election on 4 July.

When asked about the £1m by Times Radio on Friday, Reform UK’s deputy leader, Richard Tice, said he was “not aware” of it being investigated.

He said the source of the money was Fiona Cottrell. “She’s a permissible donor, she donated to the party, and that’s the end of it.”

Asked about any due diligence on the £1m, he said he had known the Cottrell family for 50 years. He added that articles about the funding were “a politically motivated smear campaign”.

He also said he understood George Cottrell was a permissible donor.

The funding of Reform UK has come increasingly under the spotlight since the Guardian revealed in April that Farage had received £5m from the cryptocurrency billionaire Christopher Harborne shortly before announcing he would stand in the general election. The prime minister, Keir Starmer, and the leader of the Conservatives, Kemi Badenoch, are among those across the political spectrum demanding that Reform be more transparent about its finances.