Police are hunting a man who indecently exposed himself to a young woman after she turned down his offer of sex at a bus stop.
The suspect allegedly approached a 27-year-old woman after she got off a route 140 bus in Northolt while on her way home from work.
The victim ran from Danemead Road towards Reading Road but the suspect caught up with her by grabbing her hands, police said.
With the help of two passers-by, she managed to free herself and escape.
The man is described as being of Middle Eastern appearance, slim and aged 20 to 25 with black hair. He was wearing a black padded jacket with a hood.
Officers from the Roads and Transport Policing Command (RTPC) are investigating the incident, which happened on Thursday, November 20.
Police have now released a CCTV image of a man they want to trace over the incident.
No arrests have been made.
Detective Constable Naomi Goodman, of the RTPC, said: "I am very grateful to the members of the public who assisted the victim and would very much like to hear from them or anyone with information relating to this incident."
Police have released a CCTV image of the suspect and ask anyone who recognises him or has any information to contact DC Goodman on 07770 315 678 or via 101.
Alternatively, they can call Crimestoppers anonymously on 0800 555 111.
