Sexual harassment and assault on the rail network is on the rise across England, Wales and Scotland but a lack of CCTV evidence is preventing justice for victims in some cases.
Claire Jones examines how broken cameras and train companies not retaining CCTV footage for long enough has been hampering police investigations. She goes on patrol with British Transport Police on the London Underground, speaks to police and victims about how frustrating it can be when key evidence cannot be accessed and sees some of the newest surveillance technology, currently not available on trains, in action.
Details of organisations offering help and support for anyone affected by sexual violence are available at bbc.co.uk/actionline Reporter: Claire Jones Producer: Nicola Dowling Technical Producer: Richard Hannaford Production co-ordinator: Tim Fernley Editor: Tara McDermott