A teenage footballer has been sentenced to at least 18 years behind bars for murdering a man at Westfield Stratford shopping centre weeks before the 2012 Olympic Games.

The throwing of a yoghurt pot sparked a mass brawl between two gangs on 29 June 2012, during which Liam Woodards – who had been out celebrating his 24th birthday – was stabbed, the Old Bailey heard.

Nii-Azu Kojo-Smith lunged forward and stabbed Woodards in the chest. As the victim lay dying, the fight moved on to Stratford tube station where one of Woodards’ friends stabbed one of the opposing group.

Following a three-month retrial, Kojo-Smith, 19, of Hackney, east London, was found guilty of Woodards’ murder by a majority of 11 to one.

The court heard that Kojo-Smith had a previous conviction for battery and threatening behaviour in 2010 after he was involved in a group attack on a passenger at Finsbury Park tube station.

In mitigation, the court heard he was a talented young footballer who was involved in coaching at Arsenal. His lawyer, Philippa McAtasney QC, said: “He was a talented footballer. He had obtained an FA1 coaching certificate and his future was set – all of that thrown away in a second of his behaviour.”

She said he knew that what he did was “very wrong” and that saying sorry to the victim’s family was not enough.

Detaining Kojo-Smith for a minimum of 18 years, the judge Richard Marks QC said: “The shopping centre at that time was full of men, women and children going about their business. It was a horrific scene of complete bedlam as many members of the public ran for safety into shops which swiftly closed their doors.

“It was readily apparent that those caught up in those appalling events must have been and were absolutely terrified.”

Tony Caton, 22, of Stratford, was convicted of two counts of violent disorder, and Anselm Legemah, 19, of east London, was convicted of one count of violent disorder. Caton was handed three years in jail while Legemah, whose girlfriend was heavily pregnant at the time, was sentenced to two years in a young offenders institution.

The judge praised the victim’s parents for their dignified conduct throughout the trial. He said: “The parents of Liam Woodards have attended every day of the trial. They have earned the respect of the court by the fact they have conducted themselves with dignity throughout in what must have been a shocking ordeal. I express hope the conclusion of the trial will bring them some closure.”