Police are appealing to the public to help them catch a pervert who struck on trains travelling through Hackney Downs and Walthamstow, and believe the man in these pictures can help them.

Hackney Gazette: The man police would like to speak to in connection with the incident.The man police would like to speak to in connection with the incident. (Image: Archant)

The first incident happened on Friday November 14, when a woman on the 12.25pm Chingford to Liverpool Street service noticed a man opposite her exposing himself and committing an indecent act.

DC Paul Cudby said: “She was understandably frightened by this, and moved to another area of the carriage with more people in it.”

The man, who got on at Clapton, left the train at Hackney Downs.

He struck again 12 days later on Wednesday November 26, when a woman told police that a man had sat opposite her on the train between Hackney Downs and Chingford and stared at her whilst he touched himself under his clothes.

The man followed her off the train at Walthamstow Central and deliberately bumped into her before getting back on the train.

The following day, Thursday November 27, police received another report of a similar incident on the 7.48am Liverpool Street to Chingford train.

DC Cudby said: “As the train travelled between Clapton and St James Street, a woman sitting on her own in a carriage was joined by a man who exposed himself before committing a sex act.

“I believe these incidents are linked. I am also confident the man in the images we are releasing today has information which will help with our enquiries. Who is he?”

Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference ESUB/B4 of 18/12/2014.

Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.