British Transport Police is appealing for help to try and trace a man who sexually assaulted a railway passenger.
The incident happened around 11.40am on Monday, March 18, between Reading and Thatcham, and only stopped when another passenger intervened.
The victim was approached by a man who sat next to her on a train from Reading.
He asked her personal questions and tried to grab her phone before becoming aggressive and sexually assaulting her.
Officers believe the man in the images may have information that could help their investigation.
Anyone who recognises him or has further information is asked to contact BTP by texting 61016 or by calling 0800 40 50 40, quoting reference 223 of 18 March.
Alternatively, call Crimestoppers anonymously on 0800 555 111.