Police are looking for this man following an assault which took place at Milton Keynes Railway Station on Saturday, May 24.
The incident occurred at around 10.30pm, when the 51-year-old victim was travelling on a Virgin Trains service from London Euston to Milton Keynes and became involved in a dispute over baggage taking up a free seat.
A man then assaulted the victim, hitting him in the back after both men left the train at Milton Keynes Station.
Officers have been carrying out several lines of enquiry, including viewing CCTV footage and speaking to witnesses to try to identify the man responsible for the assault.
Anyone with information is asked to contact British Transport Police on 0800 405040, or text 61016, quoting incident reference MSUB/B12 of 04/07/14.
Alternatively call Crimestoppers, anonymously, on 0800 555 111.