Years ago a north London solicitor told me a story which I have come to believe could be classified as a legal urban myth.

It is often fairly easy to trace the parentage of urban myths. One, the post-war story of grandma who has died and is left in the car while the family go to have coffee – when they return they find car and grandma gone – has its roots far back with the Joads’ crossing of the desert in Grapes of Wrath and even Donn Byrne’s Tale of a Gypsy Horse, whose owner has to be kept apparently alive until the Derby is run. The story of the girl abducted in a Salt Lake City department store in the 1970s can be traced to Soho and doped girls shipped to Valparaiso in the 1920s.

Then there is the choking Doberman, found by its owners on their return from a night out. When they revive it they find two fingers bitten off a burglar’s hand in its throat. Despite overwhelming evidence that it was a myth, my parents believed it implicitly. Patrick Back used to tell juries an early version in which the dog was slain by its master, who believed it had attacked and injured the child it was supposed to be guarding. Only after he had killed it did he discover that the blood on the dog and child had come from a wolf, the real attacker. His often successful aim was to show how wrong it would be to convict his man on unfounded suspicion.

My legal story involves a solicitor defending an indecency case who obtained an acquittal for a man accused of inappropriately touching his granddaughter. The father of the child stood up and yelled: ‘I’ll kill you for this.’ The solicitor then said to the bench: ‘You heard him, your worships. Bind him over to be of good behaviour.’ They bound the father over in his own recognisance of £100, a tidy sum in those days.

That evening the father walked into his local police station and put £100 in notes on the station sergeant’s desk saying: ‘Here’s your money. I’ve killed him.’ My recollection is that the father then killed himself in his cell. I’ve never found any newspaper reference to the case and, over the years, I’ve often wondered whether it was true – or was it our very own legal urban myth?

James Morton is a writer and former criminal defence solicitor