Former Daily Mirror editor Piers Morgan ordered journalists to dig for dirt on the editor of Private Eye after being mocked on a TV show a court was told today.Morgan appeared on the BBC's satirical quiz show "Have I Got News for You" in May 1996. During the programme, Ian Hislop, accused him of arranging for reporters follow him around and stake out his home. During evidence at the trial of ex-Mirror reporter, Graham Brough, it was revealed that after the show Morgan instructed Brough, who was the senior reporter at the newspaper, to carry out an investigation on Hislop. However Brough later reported back that he had found nothing scandalous about the Private Eye editor as it appeared he had led a "blameless life".In 2002 Hislop was quoted as saying about Morgan "all he's been offering for information about my private life is a £50 reward. My friends think that's not nearly enough".The revelation came during the trial of Brough over allegations that he made payments to a prison officer in exchange for information, including the inside story of singer Boy George's time in Pentonville Prison. Brough has denied being aware that his source was a serving prison officer or that he was knew paying a public official was a criminal offence.Also in the dock at the Old Bailey's court 6 are a former immigration detention officer, Mark Blake and three reporters from The Sun newspaper. After Brough's evidence had been completed one of The Sun reporters, Neil Millard, entered the witness box to discuss his contacts with public officers including another prison officer, who cannot be named for legal reasons.Millard told the jury that at the time of the alleged offences he had been a junior reporter working on the paper's night shift team, which mainly involved answering the telephone and writing a memo if any of the calls received could have led to a story. The court was shown a memo, written by the defendant, in which he reports a call from a "screw" about child murderer John Venables being "given special treatment" following his recall to jail for child pornography offences.The journalist testified that he did know the caller was a prison officer as he had asked him to send a photograph of his prison ID card to establish he would be in a position to know about Venables' treatment. He said however that he had never received any instructions or training that it was illegal to pay a public official for information and that he was not in a senior enough role to decide which stories the paper should run or who should be paid for information. Millard said that it had never occurred to him he may have been committing an offence until he was arrested in 2012.All of the defendants deny all of the charges, the trial continues.