British Transport Police want to track down a security guard they believe could hold vital information about prolific graffiti vandals who have been trashing the capital for more than 10 years.

A photo of the guard, pictured in front of some graffiti at an unknown location, was found on a suspect’s computer.

“We found this image on a hard drive and are pretty sure the man is a security guard, who may have caught vandals in the act,” said DC Colin Saysell from the Graffiti Squad on BTP’s London South Area.

“His evidence could be vital to some cases we are working on but unfortunately we have not yet been unable to track him down or identify the location.”

The group police are investigating is believed to be responsible for dozens of graffiti strikes over more than ten years across London, including in Hackney, Haringey and Waltham Forest - leading detectives to believe this image could have been taken in one of the North East London boroughs.

Anyone with information is asked to contact DC Colin Saysell on freefone 0800 40 50 40.