Two men who asked for £50,000 from an unnamed member of the Royal Family in exchanged for tapes that featured claims of gay sex have been found guilty of blackmail.

The male member of the Royal Family’s identity has been concealed during the trial. Some of the proceedings were effectively held in secret, with members of the press unable to report details in order to protect him.

Ian Strachan, 31, and Sean McGuigan, 41, have been sentenced to five years.

The court at the Old Bailey heard claims that the Royal, referred to only as witness A, performed a sexual act on his aide, witness D, at a party.

After failing to sell the story to a number of national newspapers, the pair tried to sell the tapes to a friend of the Royal.

Mr Justice Cooke said: “The corrosive evil of blackmail means that any sentence must have a deterrent effect.”

Mark Ellison QC, prosecuting, said the case was: “a classic example of blackmail.

“Although they claimed to be acting in the interests of the victim, the jury rejected this story and agreed with the prosecution that they were simply interested in the money.

“Prosecutions for blackmail are rare but it is a serious offence which can involve the victims making themselves vulnerable in order that the case comes to trial.”

He added: “We will not hesitate to prosecute blackmail cases and we will always seek to protect the anonymity of blackmail victims”.

Since The Sunday Times broke the story in October there has been widespread speculation as to which Royal Family member is the victim of the alleged blackmail.

He has been named on TV in the US and Australia and on numerous websites.

The British press are legally restrained from revealing the identity of the person, though it has been reported that he does not carry out any public duties.

Buckingham Palace has refused to comment on the case, saying only that it is a matter for the police.