Police want to trace this man over an assault on an elderly blind man who had boarded the DLR in Woolwich.
The attack, described by police as unprovoked, happened at around 8.20pm on May 1, after the 80-year-old man boarded at Woolwich Arsenal.
PC Paul Read from British Transport Police said: "During the journey the victim, who is 80, was approached by a man who had been sitting opposite him.
"Shortly before the train pulled into Canning Town station, the man placed his hand on the victim’s shoulder, and pulled him to the floor."
The victim was helped to his feet by other passengers and left the train at Canning Town, as did his attacker.
PC Read added: "Thankfully the elderly man wasn’t seriously injured as a result of the assault, but the attack was sudden and unprovoked.
"Enquiries to date have enabled me to isolate the image of a man I believe has vital information about the incident and I urge anyone who witnessed the incident or who recognises the man to contact us."
If you can help, call police on 0800 40 50 40, or text 61016, quoting reference TSUB/B8 of 16/5/2014. Alternatively, call Crimestoppers on 0800 555 111.