Nigel Farage has admitted he received a personal gift of £5m from the Reform UK mega-donor Christopher Harborne shortly before the general election in 2024.

He did not disclose that gift at the time and had made no mention of it since. That is, until Wednesday morning, when the Daily Telegraph published a story in which Farage admitted receiving the money from Harborne – saying it was for his personal security.

It’s a startling disclosure that could lead to him being investigated by the parliamentary standards commissioner. But the manner in which it came out is insightful too.

The Guardian has been researching Reform and its finances for months. The party is ahead in the polls and Farage, its leader, has said he believes he will be the next prime minister. So how Reform and its key figures are funded is a matter of legitimate – and essential – public interest.

Our reporting led to the discovery that Farage had been given £5m by Harborne in the run-up to the July 2024 election. On Monday morning, we asked both men about this. Rather than respond to the questions, they seemed to play for time.

At first, Reform’s director of communications confirmed he was the right person to handle the request. About 24 hours later, as a 10am deadline for a response approached, a different spokesperson for Farage contradicted him – and said he should have received the request for comment instead. Minutes later, a lawyer for Reform said he would need extra time to take instructions from Farage directly.

The law firm Schillings, acting for Harborne, refused to respond unless the Guardian revealed information about its sourcing and asked for more time too.

The lawyers said it was a matter of fairness to allow them to get their ducks in a row. In fact, it appears that the time was needed for something else: to brief another media organisation.

On Wednesday, the Telegraph published its story, which included Farage’s admission that he had received the £5m gift from Harborne. The Reform leader said the money had been given to help him with his personal security, and cited a firebombing at his home as a reason it was needed.

Quite apart from the clear attempt to try to get ahead of the story and dictate the narrative, there was a wrinkle in his account. The firebombing he mentioned happened last year – the year after the gift from Harborne. Prior to publication, in correspondence with the Guardian, neither Farage or Harborne’s representatives mentioned security as being an issue at all.

On Wednesday afternoon a spokesperson for Reform said the firebombing was “just one example” of the security issues he has faced.

If it was for security purposes, that still doesn’t explain why it wasn’t declared in some manner. Farage himself says that it was given “so that I would be safe and secure for the rest of my life”. He told the Telegraph: “Christopher is an ardent supporter who is deeply concerned for my safety.”

It also doesn’t explain where the £5m fits in after Farage’s election as an MP. He has been provided with security funded by the taxpayer since he became MP for Clacton in Essex in July 2024. A Reform spokesperson said he received no taxpayer-funded security.

The security of politicians – current and former – is certainly a serious issue. The MPs David Amess and Jo Cox were both killed in the course of their public service. Farage has been the subject of attacks, including having a milkshake thrown at him on the campaign trail in 2019.

But if it was necessary to have £5m to fund security so that Farage could continue his political campaigning, why wasn’t it declared to the Electoral Commission?

The money was given to him by the biggest political donor in recent history. Why did Farage not disclose it to the parliamentary authorities as a political gift?

Did the man who might become this country’s prime minister only decide to stand as an MP after being given £5m? Farage’s spokesperson said the decision was “entirely unrelated” to the gift.

Labour and the Conservatives believe the money should have been declared.

In a statement, Anna Turley, the Labour chair, said: “Nigel Farage appears to have broken the rules again by failing to declare this cash from his billionaire backer. Reform have repeatedly tried to dodge scrutiny over their deputy leader Richard Tice’s tax scandal. It’s simply not good enough for Reform to gloss over these egregious acts and further erode public trust in politics.

“It’s just the latest alarming example of Farage and his MPs believing there is one rule for them and another for everyone else.”

Kevin Hollinrake, the Tory chair, said: “As a new member of parliament, Farage was obliged to report to the House of Commons all political donations and political gifts he had received during the previous 12 months. The Conservatives are today referring Nigel Farage to the parliamentary standards commissioner.

“This £5m from the crypto billionaire Christopher Harborne raises serious questions. What is Nigel Farage hiding? And why does Reform think the rules don’t apply to them? This stinks and Reform should come clean now.”

Farage may not have been an MP when he received the gift but members of the House of Commons are required to declare any “personal benefit” they received 12 months before taking office unless it is a “purely personal gift”.

The question, then is, was it really personal?

As the guidance states: “Both the possible motive of the giver and the use to which the gift is to be put should be considered. If there is any doubt, the benefit should be registered.”