An NHS worker was brutally beaten after asking passengers to put face coverings on.
At about 10pm on Saturday, October 3 the victim noticed two men and a woman sitting close to him on the London Underground Circle Line were not wearing masks.
He walked over to them and asked why they did not have their nose and mouth covered, as is the law.
An argument erupted before one of the men punched the NHS worker several times in the side of the head.
He then threw him off the train and onto the platform at High Street Kensington station.
The group stayed on-board as the train rolled out of the station.
The victim suffered serious injuries, including a chipped jaw and three breaks to his eye socket.
Officers believe the man in the image may have information which could assist their investigation.