British Transport Police officers are appealing for information after a man exposed himself to a woman at Forest Gate station on 6 October.
Investigating officer PC Charley Sutherland-Walker said: “The victim, a 23-year-old woman from the local area, was at the station around 8.30am.
“She was approached by a man who tried to engage her in conversation, and she walked away from him as his behaviour made her feel uncomfortable", she said.
“The man then shouted at the victim and followed her. When she turned around she noticed the man was exposing himself while continuing to follow her.”