Police are appealing for information, after a security officer was assaulted and bitten as he tried to break up a fight on a train between Grange and Arnside stations.
The incident occurred on Saturday February 6 at around 8.10pm.
PC Gavin Daw said: “During a heated exchange between two passengers, one of them was punched in the face.
"A scuffle then ensued involving a number of other passengers.
“A uniformed security officer travelling on the service attempted to intervene and in doing so was hit on the head and bitten by one of the men.”
After reviewing CCTV, officers are today issuing images of a man they want to speak to about the assault.
“The man in the images is someone who I think has information about this incident. Who is he?” added PC Daw.
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference 247 of 10/3 .
Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.