The British billionaire behind a record donation to Reform UK has insisted Sir Keir Starmer's planned crackdown on political finance will not stop him from giving money to the party.

Speaking to the Telegraph, Christopher Harborne, a Thailand-based businessman, claimed he was "the reason" the government had announced a £100,000 cap on donations from British citizens living overseas.

He told the newspaper he believed he could challenge the cap in court and has not ruled out returning to the UK to get around it.

A government spokesperson said the cap on donations was part of its "decisive action to protect the integrity of our democratic system from foreign interference".

Housing Secretary Steve Reed denied the cap was designed to target Reform UK's donors, after announcing the move last month.

"The reason we are capping donations from British nationals who are living and paying their taxes overseas is that we cannot track where their funding has come from in the same way as if they're in the UK," Reed told the BBC.

"So you could have situation where the Russians, Chinese, Iranians, hostile states, could be funnelling their money through those individuals to influence UK elections."

The Telegraph interview comes as Reform UK leader Nigel Farage faces questions about a £5m gift Harborne had given him before he became an MP.

Harborne, who until now had kept a low profile, said he wanted to speak out to explain his motivation and his relationship with Farage.

Farage said he had been given the £5m gift to pay for personal protection "so that I would be safe and secure for the rest of my life".

But Labour and the Conservatives have accused Farage of breaking parliamentary rules by not declaring the £5m gift in the register of interests for MPs - and the Tories have referred the Reform leader to Parliamentary Standards Commissioner.

Farage's team say there was no requirement to declare the money because it was a "personal unconditional gift that was given before he was elected".

Last year, Harborne donated £9m to Reform UK - the biggest single donation to a UK political party by a living person.

The cryptocurrency investor and aviation entrepreneur gave £12m in total to Reform UK in 2025.

Harborne has previously given large sums to the Conservatives under Boris Johnson's leadership, as well as Reform's predecessor the Brexit Party in 2019 and 2020.

In March, the government announced changes to "protect UK democracy from scourge of foreign actors and financial influence", including an annual £100,000 cap on donations from British citizens living abroad.

At the time, Reform UK's home affairs spokesman Zia Yusuf accused Labour of "choking off legal funding for its main rival".

Harborne echoed that view in his interview with the Telegraph, telling the newspaper: "I think I'm the reason for that legislation."

He added: "I don't believe the government has a right to stop me, and they won't. There is always a way, we just don't know what it's going to be yet."

Reform sources told the BBC Harborne's £5m gift to Farage, which was reported by the Guardian, was given to him in early 2024, ahead of the general election that year.

A Reform UK spokesman said: "We are confident everything has been declared in accordance with the rules."

The Commons code of conduct states that new MPs "must register all their current financial interests, and any registrable benefits (other than earnings) received in the 12 months before their election within one month of their election".

The rules say "purely personal gifts or benefits" from family or commercial loans would not normally have to be registered.

But the rules say "both the possible motive of the giver and the use to which the gift is to be put should be considered", adding "if there is any doubt, the benefit should be registered".

The Liberal Democrats have said Farage "must come clean on whether he promised anything to Harborne in exchange for this eyewatering amount of money".

But Harborne told the Telegraph he was not "expecting anything in return apart from ensuring [Farage's] safety".

The newspaper also reported that a legal document was signed stating that the gift was "unconditional and irrevocable".

In his Telegraph interview, Farage said Harborne had become concerned about his level of protection when a milkshake was thrown at him in 2019, as he was campaigning in Newcastle for the Brexit Party.

"I have tried and failed in the past to get security funded by the Home Office and I don't think the state will ever help me," Farage told the newspaper.

"I'm very much on my own and will be for the rest of my life, and I have to face up to that grim reality.

"Christopher is an ardent supporter who is deeply concerned for my safety."

Reform UK sources say Farage's team notifies local police forces of his movements when he is travelling, in line with Operation Bridger protocols.

Operation Bridger is a national police programme that offers MPs access to extra security in their homes and constituency offices.

Party sources say Farage does not receive protection from the Home Office or police, and travels with his own private security team.