Offenders are helping to get London looking spick and span for the upcoming royal wedding of Prince William and Kate Middleton under a scheme run by the London Probation Trust in partnership with local authorities. The 'Community Payback' project sees low-risk offenders cleaning the walls of a tunnel leading to a central London underground tube station, a task they will carry out in the run up to the royal nuptials on April 29.Duration: 01:21