Police have released this CCTV image of a man they think could help them after a man exposed himself to a 16-year-old boy on a train.
The boy boarded the train at Guildford at 11pm on Tuesday 20th May and sat in the third carriage from the front.
Shortly after the train left, a man sitting near the boy exposed himself and began behaving inappropriately.
The boy moved and told the train guard what happened.
The guard saw the man leave the train at Ash station.
Detective Constable Tony Bronger said, "I urgently want to speak to the man pictured as I think he has crucial information about what happened. If you recognise him, please get in touch. I am also keen to hear from anyone who was on the train and may have witnessed the incident."
Anyone with information is asked to contact British Transport Police on 0800 40 50 40 quoting reference number SSUB/B8 of 30/06/2014.