Police are hunting a flasher who exposed himself on a train in Worksop.
The incident happened on the 5.26pm Nottingham to Worksop service in December in front of a ‘carriage full of shocked passengers’.
A CCTV has been released of a man police want to trace over the incident.
Detective Sergeant Paul Kazimierczyk, of British Transport Police, said: “We have been following a number of enquiries to try to identify the person responsible for this offensive and intimidating act.
“Nobody travelling on the railway should have to put up with this type of behaviour and we’re determined to find the man responsible.
“We believe the man captured on the on board CCTV can help us with our enquiry. If you think you can name him, or if you have any information to help our investigation, we’d urge you to get in touch.”
Call British Transport Police on 0800 40 50 40.