The victim of the vicious attack approached a man on the train at around 5.30pm on August 12 and asked him to put a face mask on.
Following this, an argument broke out and the man squared up to his victim before headbutting him to the floor and punching him numerous times.
The victim suffered serious facial injuries from the attack.
British Transport Police have said they believe the man in the photo may have information which could help the investigation.
Anyone who recognises the man have been asked to contact the British Transport Police by texting 61016 or calling 0800 40 50 60 quoting reference 444 of 12/08/20.