A renewed appeal has been issued for any information relating to the disappearance of Lee Boxell from Sutton in 1988, after the case was featured on Crimewatch Roadshow.

Lee, who was 15 years old when he disappeared 31 years ago this month, vanished after last being seen in Sutton High Street at 2.20pm on the afternoon of September 10.

The case has been periodically investigated over the decades, with the original line of enquiry suggesting Lee had been travelling to watch a football game at Selhurst Park when he vanished.

But the time between Lee’s last sighting and the kick-off at the match at 3pm would not have been sufficient time for him to have travelled to the match.

Your Local Guardian:

A review of the circumstances of his disappearance later provided evidence to suggest that Lee visited an unofficial youth club in an out-building at St Dunstan's Church, in Church Lane, Cheam, known locally as ‘the shed', where young people were known to gather to drink and smoke.

Detectives believe that Lee visited the shed on the afternoon of Saturday, September 10, the day of the last known sighting, where he witnessed someone, probably a teenager, being sexually assaulted. It is believed that he either intervened to stop that assault or threatened to report it.

It is also believed that he was subjected to an assault in order to stop him from identifying and exposing the suspect, and that this assault proved fatal.

In the Met Police’s longest ever forensic archaeological dig, a year was spent excavating St Dunstan's churchyard, but nothing was found.

Your Local Guardian:

Review officer John McQuade, from the Specialist Crime Review Group, said: “I would like to appeal to that young person who was sexually assaulted to come forward.

“Your evidence would confirm Lee’s presence at the shed and help to identify his assailant.

“I believe that Lee was assaulted by one person and that they had help from one or more others to dispose of his body and/or cover up the death. I would appeal to those people to come forward and confirm this and help us to locate Lee’s body.

“I accept and wish to make it clear that it may not have been the intention to kill Lee and that your role in assisting the main attacker will be taken into account. But you have to take responsibility for your actions and face the consequences before it is too late for Lee’s family.

“Someone knows what happened to Lee and where his body is buried.”

Anyone with information is asked to call the Sutton incident room on 0208 721 4005 or Crimestoppers 100% anonymously on 0800 555 111.