Police have launched an appeal after a man performed a sex act in the Clapham Junction station toilets near to a sixteen-year-old boy.
Officers said just before 10am on November 17, the boy left one of the toilet cubicles and encountered a man masturbating next to the urinals.
They said they believe the man in the images may have information which could help their investigation.
If you recognise him, or have any information, they ask the public to contact the British Transport Police by texting 61016 or calling 0800 40 50 40 quoting reference 2200119638.