Detectives investigating an attack on a ticket inspector by a suspected fare dodger at London Bridge station have released CCTV footage of a man jumping over the barriers and punching the victim in the face.
The 26-year-old station worker was knocked to the floor after a man with a 16-25 ticket refused to show his Young Persons railcard.
The man then vaulted back over the ticket barriers and ran out of the station.
Police were called to the scene within minutes but could not find the attacker.
The victim was left "shaken up" with a "nasty injury to his jaw" after the assault at 3.20pm on July 30, police said.
Detective Constable Rod Harbron, who is leading the investigation, made a renewed appeal for witnesses to speak to police as new CCTV footage was released.
He said: “This was a violent and unprovoked attack which left the member of staff incredibly shaken up and with a nasty injury to his jaw.
“Members of rail staff do an incredibly important job and have the right to come to work every day without the fear of violence or abuse.
“I want to hear from anyone who recognises the man in the video, as I urgently need to speak with him. I also would like to hear from any witnesses who have yet to come forward to police.”
Anyone with information can contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference S-SUB/B17 of 29/10/2014 or speak to Crimestoppers anonymously on 0800 555 111.
