John Masterson, who is suing the Metropolitan Police for wrongful imprisonment and malicious prosecution, was a personal friend of Ronnie Kray who had assaulted police officers and taken hostages in prison.
Dr Marshall told the court that Mr Masterson had "an anger and bitterness towards Ms Harman". He had gone on hunger strike outside the Labour Party's offices and had written to the Queen about his plight.
After two interviews with him, Dr Marshall, then a junior psychiatrist at Maudsley Hospital, in London, decided to breach her duty of confidentiality and ring Ms Harman, leaving three messages at the House of Commons in July 1989. She told the court that Mr Masterson had told her that he went to bed "thinking about killing her".
Dr Marshall recalled that the MP "knew that it referred to John Masterson, saying: `It's about John Masterson, I know it is about John Masterson.' Dr Marshall explained that she had not intended to name Mr Masterson at this point but she described Ms Harman as "almost hysterical" and "mouthy about the medical profession and psychiatrists".
In a consultation with a more senior psychiatrist it was agreed that Mr Masterson did pose a risk to the public and Ms Harman. But Dr Marshall said she did not think he would carry out the threats.
Mr Masterson told the court that he had met Ms Harman on only three or four occasions and had not intended to kill her. He said: "If I was going to kill anyone they would be the first and last person to know it. I would not kill anyone."
The jury was told Mr Masterson bore a grudge against the Peckham MP for allegedly "selling him down the river". In 1980 Ms Harman had been representing him in his fight against the Home Office, which he claimed had breached his human rights with the harsh treatment he received in solitary confinement. But a High Court judge found that his human rights had not been abused. He was also aggrieved at having lost his legal aid.
Mr Masterson was arrested and charged with threatening to kill Ms Harman in July 1989, but after being held in Brixton prison he was released.Reuse content