I have often wondered just how many of my old cases resulted in miscarriages of justice. Men and women who were wrongly convicted as opposed to those who were wrongly acquitted, that is.

In those days, justice in the lower courts was something of a conveyor belt. Once on, never off. Some of the accused, clearly mentally ill, should never have been charged. I remember being the only solicitor around at the end of a morning at an Inner London court when I was asked to defend a ragged, bearded man in a duster overcoat, charged with stealing letters from an office building where the postman had dumped them in the doorway.

Legal aid was handed out but I had to defend him on the spot. There was to be no question of pre-trial mental and medical reports. Our conversation was Pythonesque. Yes, he had taken the letters. ‘Why?’ ‘I was taking them to Elizabeth Taylor’ (pictured). ‘Why?’ ‘Because I’m Elizabeth Taylor’s doctor.’ ‘Yes, but these aren’t addressed to Miss Taylor.’ ‘No, but I have to take her ALL letters.’

Injustice was swift and on conviction he was returned to the mental hospital from which he had escaped the previous day. Just what was the point of it all? Several offices were deprived of their mail for 24 hours. Some young officer had secured a conviction which would count to his promotion. I earned an extra fiver for the few minutes the whole farce took, but the poor man had another conviction added to his record and I doubt very much he understood why.

There was another case  which, 50 years later, I remember with shame. I prosecuted a woman for stealing a tin of salmon from the local supermarket. Her defence was that it had leaped off the shelf into her bag. ‘Was it spawning time?’ I asked wittily.

She was convicted, had a previous and went to prison for 14 days; which was pretty standard in those unenlightened days. Within six months she and her husband were in my office asking me to defend her in another shoplifting case.

‘Ask her the name of the Queen,’ he said. ‘Ask her what day or month it is.’ The poor woman remained mute. She was suffering from rapid and early dementia.  One thing this taught me was not to be unkind to, or clever at the expense of,  defendants or witnesses.

James Morton is a writer and former criminal defence solicitor