A young man died as a result of an "unprovoked" attack on board a train, after saying to his assailant "wagwan", a court has heard.

Graphic designer Rhys Stacey Parchment, 25, is standing trial at Blackfriars Crown Court charged with the manslaughter of 24-year-old Warsame Warsame, who was living at YMCA Surbiton. He is accused of punching Mr Warsame twice in the head on a train travelling between Raynes Park and Wimbledon on March 2, 2013. Mr Warsame was found unconscious on a different train an hour later, and died in hospital from a bleed on the brain on March 4. The court heard how Mr Stacey Parchment had boarded the train at Surbiton, on his way to play football.

Mr Warsame boarded the train at Raynes Park, and walked through the carriage Mr Stacey Parchment was sitting in, he court heard. Passengers reported hearing Mr Warsame say "wagwan" - a popular greeting spoken in a Jamaican patois - before Mr Stacey Parchment got up from his seat and confronted Mr Warsame, Miss Johnson said. Mr Stacey Parchment punched Mr Warsame once in the head, sending his head back and striking an interconnecting carriage door, she claimed. A second blow, also to the head, put Mr Warsame on the floor, it was claimed. The prosecution claimed witnesses heard a female passenger tell Mr Stacey Parchment he should not have punched Mr Warsame.

The jury was shown CCTV stills of Mr Warsame on board the train holding his head, before slumping across two seats. But the court heard there was no CCTV of the fight itself, because a camera in the carriage was not working.

Mr Warsame was found unconscious and snoring between Wimbledon and Raynes Park. The court also heard how the 24-year-old had a pre-existing medical condition requiring regular dialysis. He was also on anti-psychotic medication, following an attack inside a Kingston nightclub in 2007 that had altered his behaviour, the court heard. But he had not taken the drugs the day before the attack, and had punched a fellow resident three times in the face earlier that morning, the jury heard. Mr Stacey Parchment, of New Barns Avenue, Mitcham, denies manslaughter. The trial continues.