Police are searching for this man after a commuter was punched in the face as he tried to board a train at Stratford station.
The 20-year-old man was barged and then attacked as the 3.57pm service to Shenfield pulled into platform 8 on January 7.
A scuffle broke out as the victim tried to defend himself, but he soon after fled the east London station.
He was left with swelling to his face, police said.
Detective Constable Lawrence Murphy, who is leading the investigation, appealed for witnesses to the attack to come forward.
He said: "Violence on the railway network is completely unacceptable and we will do everything we can to bring offenders to justice."
Anyone with information should contact British Transport Police on 0800 40 50 40, text 61016 quoting reference LUA/B6 of 14/01/14, or speak to Crimestoppers anonymously on 0800 555 111.
