A 62-year-old woman was knocked unconscious after being punched in the face at Green Park Tube station. The victim fell and hit her head on the floor after her attacker accused her of staring at him.
DC Mortimer from British Transport Police said: "This was a shocking, callous and unprovoked assault. I'd urge anyone who recognises the man pictured, or has any information that could help our investigation, to please contact us."
The attack happened around 6.40am on Monday, 23 December 2013. Anyone with information should contact British Transport Police on Freefone 0800 40 50 40 quoting reference LUA/B4 of 09/01/14.
A new Bomber Command memorial will be unveiled today, for the 55,000 airmen who lost their lives during World War II.
The £2m memorial will be unveiled by the Queen in Green Park.