Earlier this year James Orr, the party’s Head of Policy, and Dan Jukes, a close aide to Nigel Farage, arranged for a US company to secretly fund three influential polls that were commissioned by the party.

Mr Orr and Mr Jukes did not know that the supposed donors behind the US company were actually an undercover team from Verbatim posing as a wealthy American and his UK-based son, “William Lockwood”.

The US company that made the poll payments and the supposed American financier, resident in the US, are not permissible donors under electoral law. Donations of this size must be declared to the Electoral Commission.

Mr Jukes also proposed a scheme to get a larger sum of money into the party by having the American father donate via his UK-resident son. This would be illegal.