Police are hunting a man who carried out a solo sex act while staring at a woman passenger on a London Underground train.
The victim was travelling between Balham and Old Street when the incident happened.
He sat opposite her and began masturbating on the Northern line Tube carriage at around 11.40pm on August 22 last year.
An image taken on a mobile phone shows a male dressed in a red designer jacket clutching what appears to be a Valentino bag and wearing Apple AirPods.
British Transport Police appealed to anyone who may have experienced similar incidents to come forward.
A spokesman said: “Detectives would like to speak to the man in the image who they believe may have information that could help their investigation.
“All reports of sexual assault are taken seriously and any information provided can help build a bigger picture.”
Anyone who recognises the male is asked to contact BTP by texting 61016 or calling 0800 40 50 40, quoting reference number 2400106476.
Alternatively, they can contact the independent charity Crimestoppers anonymously on 0800 555 111.
