A teenager has been found guilty of murdering South Norwood 14-year-old Kevin Ssali after a petty dispute over a woolly hat.

Roree Cox, 18, stabbed to death Kevin, of Whitworth Road, on a bus in Lewisham on September 15, 2012.

Cox, of New Cross, carried out the killing as the bus travelled down Burnt Ash Road in Lee Green.

During a trial at the Old Bailey, the jury heard how Cox's 15-year-old brother Chay had argued with Kevin about his designer watch and woolly hat as he sat next to him.

Prosecutor Sean Larkin told the Old Bailey that Crown Wood College pupil Kevin had "made comments to the 15-year-old boy about his woollen hat and large designer watch".

Chay then called his elder brother, who was travelling on the bus behind and had a history of hostility with Kevin, to alert him about the dispute.

Cox raced onto the bus while two friends held the door open, pulled a hidden blade from his shoe and shouted, "Do you want me to stab you?", before knifing Kevin and running from the bus.

Today this CCTV footage was released from the night of the murder

Police said the attack lasted no more than five seconds.

Cox denied murder but was found guilty unanimously this morning. He will be sentenced on February 28.

Detective Inspector John Marriott, who led the Metropolitan Police's investigation into Kevin's murder, said: "I would like to use today's verdict as an opportunity to thank all those people who have been brave enough to talk to us and help piece our investigation together.

"I know that Kevin's family appreciate the part they have played in seeing justice done for him.

"The events that led to Kevin's death started as an exchange between two boys that wasn't violent, or threatening to other people on the bus.

"Roree Cox's actions show a young man who was carrying a knife, and prepared to use it. He stabbed Kevin without even considering if his brother was in danger or if Kevin, who was unarmed, could fight back."

Kevin had been been missing for two months before his murder.