A man was sexually assaulted on the London Undergound after asking another passenger if he was on the correct train.
The incident happened on a Northern Line tube around 10.25pm on Sunday, August 6.
The victim boarded a northbound service at Kennington, before approaching another man who had embarked at the same time as him, and asking whether he was on the correct service.
The man then sexually assaulted him.
The victim moved to another carriage.
British Transport Police (BTP) have now issued a CCTV image of a man they believe may have information which could help their investigation into the incident.
If you recognise him, or have any information, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 2300092243.
Information can also be given anonymously to Crimestoppers on 0800 555 111.