American writer Dominick Dunne always believed that the lenient verdict of involuntary manslaughter in the trial of the man convicted of strangling Dunne’s niece reflected the fact that the jury noticed that he sat in court with a Bible.

I doubt this would have worked here. I recall a long trial with a number of defendants who, thoroughly bored with long legal argument, played cards under the watchful eye of the dock officers. I could not see what the fuss was about when someone reported it to the judge. At least they were not causing trouble, as did some Australian defendants who managed to smuggle a bag of their faeces into court – which they then threw at the jury.

American lawyers have always tested highly on the appearance of their client and making him look acceptable to the jurors. Michael Connelly, in his novel Gods of Guilt, has his lawyer buy clothes for the client.

This is not just make-believe. I watched a trial in California where the defendant was accused of drowning his wife.  The defence team was at pains to make him appear sympathetic and sent out one of the staff to buy a pale grey jacket and a pastel shirt and tie, which they thought looked better than a suit. It did not help. He was convicted.

I never had much influence on how my clients dressed. I did persuade one man charged with public order offences that wearing a West Ham scarf would not appeal to the local bench. But when I suggested to a biker charged with murder that it was not a good idea to wear his colours in court he changed his lawyer rather than his clothes.

One client of mine knew exactly what he should do. A cat’s meat vendor from the suburbs charged with a confidence trick, he turned up wearing a Brigade of Guards tie in front of the formidable Ewan Montagu at what was then the Middlesex Sessions. His counsel was told that if he was wearing it by the afternoon, Montagu would allow the prosecution to put his character in. Fortunately he was on bail and it was not a long walk down the road to the Army & Navy Stores.

James Morton is a writer and former criminal defence solicitor