Martin Peckham, 41, has been accused of threatening to kidnap the daughter of Formula 1 tycoon Bernie Ecclestone.
The divorced father-of-two allegedly threatened to take the heiress unless he was paid £900,000, reports The Sun.
Prosecutor Philip Lemoine said: "This was a crudely-executed, perhaps not frivolous but rather amateurish, attempt to obtain money from Mr Ecclestone.
"Amateurish it might have been, but it was a targeted offence. The family is vulnerable and Mr Ecclestone took it seriously. The impact on Tamara Ecclestone as a human being has been significant in her home and working life."
The court was informed that no money was ever exchanged after the series of phone calls.
Peckham was bailed, and has been ordered to return to South London's Southwark Crown Court on Friday (July 13) to face blackmail charges.
Judge Justin Barron told him: "If you do attempt to contact them in any way - directly or through another person, by email or phoning them up - you'll be in breach of your bail and be brought back to custody."
In a separate case, two men are also awaiting trial for attempting to extort £200,000 after threatening to release details of Tamara Ecclestone's private life.