A man 'inappropriately touched' a woman on a Central line train and only stopped after she shouted at him.
Detectives from British Transport Police (BTP) are investigating the incident which is believed to have happened at about 5.45pm on Tuesday, May 19.
The 40-year-old victim was travelling on an eastbound Central line train when a man boarded at Holborn and allegedly began to inappropriately touch her in the crowded carriage.
BTP said the man only stopped when the woman shouted at him and he left the train at St Paul's.
Police are now appealing for help in identifying a man in CCTV images who they believe can help with enquiries.
Detective Contable Allan McTaggart said: “Who is the man pictured in these CCTV images? That’s the question I need the public’s help to answer.
"We need to speak to him about this offence as we believe he will be able to assist the investigation
"This was understandably a truly shocking incident for the woman and something nobody should have to experience.
"We always fully investigate all reports of unwanted sexual behaviour on the Underground and are doing all we can to catch the person responsible."
Anyone with information should contact British Transport Police on 0800 40 50 40, or text 61016, quoting background reference T/B5 of 04/08/2015. Information can also be passed to Crimestoppers anonymously on 0800 555 111.
