I prepared my first criminal report, for a defendant's solicitors, when I was an honorary senior registrar in about 1981. It was a salutary experience. The solicitors sent the report to their client. He was remanded in custody. Notwithstanding the confidentiality that attaches to communications between prisoners and their solicitors, the prison authorities read my report. They contacted my consultant to ask him if he thought that it was a good idea for the prisoner to read my opinion about him. Needless to say, in trying to uphold the ethical principle of doing justice, I had fallen foul of the principle of doing no harm.

It was the beginning of a steep learning curve. Since then I have had 30 more years of preparing expert psychiatric reports and giving evidence in various courts. I use the term ‘court’ for any court of law, tribunal or body concerned with the process of arbitration or dispute resolution or professional conduct committee or panel.

I have given evidence to an agricultural land tribunal. It was convened in the lounge bar of a Yorkshire Dales country hotel. The tribunal sat in a raised area, usually occupied by the band. The parties, the witnesses and experts sat at small tables but without the customary pint. We were surrounded by pictures of sheep-shearing and cattle markets, including Sheep Shearing at Hawes. I purchased this as a leaving present for a colleague who kept his own sheep.

I have given evidence in the panelled court rooms at the Royal Courts of Justice. There, enticingly for me, if no one else, the side walls are lined from floor to ceiling with bookshelves teeming with the law reports of the last two centuries. The most conspicuous signs of the 21st century are the laptop computers of the judges and counsel.

At the beginning I was fortunate to be trained by Dr Angus Campbell. I owe an enormous debt to many more psychiatrists, and lawyers, than I will go on to acknowledge by name. In the early 1980s, training as a psychiatric expert witness was very much on the apprenticeship model, if you were fortunate, as I was, to begin preparing reports as a trainee. If not, and as it was for me once I became a consultant, it was a case of learning on the job.