Why we're now seeing more graffiti on the Tube

Transport for London (TfL) says it is removing about 4,000 pieces of graffiti per day on the Central and Bakerloo Tube lines.

It says it is dealing with a huge increase in vandalism on the trains as well as challenges in getting the trains cleaned.

TfL says it has a reduced number of trains on the Central line as some are being upgraded, five at a time. The Bakerloo line has the oldest fleet, and hence it has fewer trains.

BBC London's Transport and Environment Correspondent Tom Edwards has the story.