One of the men accused of blackmailing a member of the Royal Family in a gay sex blackmail case has told a court at the Old Bailey that he was intending to reveal a “predatory homosexual”.

Ian Strachan, 31, said that he taped claims made by a royal aide, known as witness D, in order to inform the unnamed Royal (witness A) of his employee’s behaviour.

Mr Sreachan claimed that Witnesses D tried to drug and assault him and two of his friends.

He claimed that was the main motive for his alleged polot with Sean McGuigan, 41, to make recordings of Witness D speaking about the unnamed Royal.

He told the court he didn’t wish to make any money, merely prove to the Royal, who he considered a friend, that his employee was acting inappropriately. He even claimed that he and Mr McGuigan discussed publishing clips of the recordings onto Youtube.

Mr Strachan said that a journalist from the News of the World said that the tape recordings he had made could be worth as much as £50,000 ($100,000).

He also told the court that a friend of the Royal, known as witness C had offered €73,000 (£57,500/ $114,000) for the tapes. He told the court that he did not ask for money “because that would have been blackmail.”

Mr Strachan admitted that he had falsely claimed in the past to hold a law degree from the University of Edinburgh.

Since The Sunday Times broke the story in October there has been widespread speculation as to the identity of the Royal Family member who 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 alleged blackmail plot, saying only that it is a matter for the police.

Mr Strachan and Mr McGuigan are both pleading not guilty to making demands with menaces, contrary to the Theft Act 1968.

The trial continues.