The standards watchdog has been urged to investigate whether Nigel Farage lobbied the Bank of England to drop a cryptocurrency plan that could be costly for the billionaire bankrolling his party, potentially in breach of parliamentary rules.

The Reform UK leader has said his party’s major donor, Christopher Harborne, wanted nothing in exchange for the £15m he donated to the party and the undeclared £5m gift to Farage the Guardian revealed in April.

But Farage used a private meeting at the Bank to urge its governor, Andrew Bailey, to drop plans for a state-run alternative to the digital currency that has made Harborne, his Thailand-based benefactor, one of the richest people in the world.

As reported by the Guardian last month, Farage…