A 13-year-old boy was arrested at school for carrying a revolver and bullets – but his lawyer criticised the charges.

She said the firearms charges at Wimbledon Youth Court should never have been brought as the revolver in question could be more than 100 years old and might not be working.

She said: “As a result of being charged with this offence he has been expelled from school. He has been charged with an offence that is putting his education at risk.”

Legal restrictions mean neither the child nor his school can be named, and Merton Council has declined to comment on how the gun was discovered.

The case has now been put back by a month so forensic tests can establish the age of the weapon, a Smith and Wesson revolver.

The boy, who was arrested on January 20, has not entered a plea to the charges he faces.

His lawyer said the boy was held in custody for 27 hours before being charged – and was then released on unconditional bail.

She added: “On the basis of the evidence this is not a firearm and my client is not guilty. My client needs to know what’s happening.”

The boy has been charged with one count of possession of a revolver, and two counts of possession of ammunition.

Guns and the law

Illegal possession of a handgun could lead to a prison sentence of five years under Home Office guidelines – although antique weapons can be exempt.

Firearms expert David Dyson, who is a trained lawyer with 25 years experience in the field, said there was no set age that made a gun an antique and the legal defence relied on how the weapon was stored and used.

He said: “It’s up to the jury to decide these things on a case by case basis”.

He said Government guidance to police forces had suggested firearms produced before 1939 were likely to be antiques, but this had never been tested in court.

Mr Dyson said charges relating to possession of guns applied if any part of the gun was in working order.