Farage suggests he believes investigation into £5m gift will find against him

Under Commons rules, new MPs are required to register any gifts worth more than £300 they received in the previous 12 months, except where it “could not be reasonably thought by others” to relate to their political activities.

Mr Farage was asked about the interview as he appeared on the BBC’s Sunday With Laura Kuenssberg.

He replied: “Under the rules of Parliament, if I even answer your question, I will receive a letter of rebuke from the standards commissioner.

“This is the farce of it: You can say what you like, people can write what they like, I’m not allowed to respond.

“But to hell with it: Yes, I have been interviewed about it, and you know what?

“If Ann Widdecombe’s murder at the age of 78 doesn’t justify me being able to pay for my security to whatever level is needed for the rest of my life then I don’t know what is.”

Asked if he expected the commissioner to find against him, Mr Farage replied: “Do I think the establishment would find against me, the leader of an insurgent party? What a question to ask.”

Mr Harborne is one of two crypto-billionaires who donated £72 million to Reform.

The twin £36 million gifts from Ben Delo and Mr Harborne reignited calls for a blanket cap on donations, going further than legislation aimed at restricting donations from overseas sources.

Mr Harborne was based in Thailand, but in June he was reported to have registered to vote in Hampshire.