The incident occurred on March 21 at 10pm when a man on the platform attacked the train with a screwdriver and threw it at the train guard, hitting him in the face.
The guard received stitches to a wound on his forehead and attended the hospital.
The suspect is described as a white male in his late 20s who wore a baseball cap and tracksuit at the time of the incident.
Anyone with information is urged to contact BTP or Crimestoppers anonymously.
