Detectives hunting a graffiti artist believed to have caused more than £1 million of damage across London have issued a public appeal for help.
Scotland Yard said the vandal has scrawled their distinctive "ZERX" tag on houses, schools and the Tube network in boroughs across the capital including Harrow, Brent and Westminster.
The graffiti was also daubed on the side of the Admiralty building in Whitehall following student protests last December.
Detective Inspector Paul Armstrong, of the Specialist Crime Directorate, said: "Using this type of graffiti not only looks very unsightly but can also cost councils, London Underground and members of the public a considerable amount of money to remove.
"This tag has been scrawled across residential homes as well as schools, sheltered accommodation and historical structures and I would appeal to anyone who has information about the person who is responsible for this to contact police."
A 21-year-old man was arrested in January by detectives investigating the spate of vandalism and was released on bail. He is due to report back to police next month.
Anyone with information is asked to call police on 020 8246 0050 or Crimestoppers anonymously on 0800 555 111.