Police have released a CCTV image in the hunt for a flasher targeting woman on trains.

It follows three incidents on the Overground line between Chingford and Liverpool Street.

A woman on a train travelling to Liverpool Street noticed a man exposing himself and committing an indecent act at 12.25pm on November 14.

The man had got on the train at Clapton and got off at Hackney Downs.

On November 26, police believe the same man stared at a female passenger sitting opposite him on a train between Hackney Downs and Chingford.

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

The following day a woman was sitting on her own in a carriage when she was joined by a man who exposed himself before committing a sex act.

The victim left the train at Walthamstow Central.

Investigating officer, Detective Constable Paul Cudby, said: “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.