The father of Lee Boxell has pleaded with the public to help “ease our years of pain” and reveal if his son was murdered, 35 years after he disappeared at the age of 15.

The Metropolitan Police have issued a fresh appeal for information about the teenager’s disappearance and Crimestoppers is offering a £20,000 reward for information that leads to the recovery of his remains.

Lee left his home in Sutton, south London, to go shopping on September 10 1988, the force said.

He met a friend and they parted company at around 1pm.

The police said the last confirmed sighting of Lee was in Sutton High Street at around 2.20pm.

There have been no other confirmed sightings of him in the 35 years since.

Lee’s parents, Peter and Christine Boxell, have said they are desperate for their son to be returned to them.

Mr Boxell said: “We have not seen or heard from our dear son Lee since he went to Sutton, 35 years ago, on 10th September 1988.

“He was only 15 when he disappeared. We fear that Lee may have been murdered.

“We are still hoping that someone will come forward to help find his remains, so that my wife and I can say goodbye to our beloved son before it’s too late for us (we are in our late 70s).

“If you can help us and his sister finally know what happened and have some closure, please, do what’s right.”

He added: “This really does give someone a chance to do the right thing and help ease our years of pain. We can then see Lee finally laid to rest.”

He asked anyone with information to contact the police on 020 8721 4005 or to contact Crimestoppers anonymously.

Detective Chief Inspector Kate Blackburn said: “While we don’t have conclusive evidence that Lee came to harm, with no sightings or credible information in 35 years we sadly believe that Lee is no longer alive.

“Over the years we have interviewed a number of people who we believe were involved in, or know about, Lee’s disappearance. When arrested, those people gave a number of conflicting accounts.”

Some 24 years after he went missing, police learned that Lee used to visit an outbuilding at St Dunstan’s Church, dubbed “the Shed”, a gathering place for teenagers which was targeted by sexual predators.

In 2014 three men were arrested on suspicion of murder, but they were later released on bail.

Ms Blackburn added: “My hope is that someone who didn’t feel they could speak to us in the past may now feel that they can come forward and share what they know.

“At this stage of our investigation my priority is to find Lee so that he can be returned to his parents. Lee’s parents deserve answers and they deserve the opportunity to bury their much-loved son.

“Your information could help end the suffering for Lee’s family. If you can help, anonymously or otherwise please do get in touch.”