A youth is facing years behind bars for hacking to death a teenager with a deadly "Zombie Killer" machete.
Stefan Appleton, 17, was fatally stabbed with a 25in (63cm) long serrated blade which the attacker claimed he had found stashed in bushes around a park in north London.
An Old Bailey jury deliberated for 14 and a half hours to convict the 17-year-old defendant of manslaughter but clear him of murder.
His alleged getaway scooter driver was cleared of murder while another youth, also 17, was acquitted of conspiracy to cause grievous bodily harm.
As the jury delivered its verdicts, there were gasps from Stefan's family before they left the courtroom in tears.
The conviction comes just days after Home Secretary Theresa May announced plans to ban the sale, manufacture and importation of Zombie Killer knives which she said "glamorise violence and are clearly targeted at young people".
The trial had heard how student Stefan had been playing a game with friends by Nightingale Park in Islington, where children were enjoying the summer evening on the swings and slides on Wednesday June 10 last year.
His 17-year-old attacker jumped off the back of a stolen scooter, pulled out the machete-like blade and chased after Stefan and his friends, the court heard.
When Stefan tripped and fell, he was stabbed by the boy while on the ground. He died later in hospital.
As the killer rode off on the back of the moped, he allegedly shouted out "RP", standing for Red Pitch, a rival to another gang in the Nightingale Park area.
He fled to Bristol and tried to arrange a flight to Malaga in Spain before returning to lie low in London, but he was arrested within days.
In his defence, the youth, who cannot be named, said he had come under attack when he went to snatch back his bicycle which had been stolen by another boy.
Prosecutor Simon Denison QC cited Stefan's death as another "tragic waste of a young life" taken by a knife.
He told jurors the Zombie Killer had "no legitimate purpose" and, while it sounded like a toy, it was anything but.
The weapon was never found but police were able to identify it from the sheath which had been dropped on the ground.
During their searches around north London, police seized three more Zombie Killer knives and an assortment of other blades, including a machete. None were connected with the killing.
The Zombie Killer knives were found at the nearby Britannia Leisure Centre in Gopsall Street, London Fields, and Hackney.
A seven inch serrated kitchen knife was found in bushes near Nightingale Park, another was seized from a community centre while a member of the public handed in a machete stashed under another bush.
The boy who carried out the attack had a previous conviction for possessing a blade from the year before.
When he was caught with a lock knife in a McDonald's restaurant, he told police he bought it because it "looked nice".
Zombie Killer knives are available on the internet for as little as £10.
Earlier this year, Alf Hitchcock, Chief Constable of the Ministry of Defence Police and lead on knife crime for the National Police Chiefs' Council, said in an interview: "These are absolutely horrific weapons for which there can be no legitimate use.
"Whilst we haven't got significant evidence of a huge increase in sales, there is enough evidence for it to be worrying and we are looking to work on a form of words that bans these weapons."
Under the Home Secretary's plans outlined during a speech at a crime and policing conference offenders would face up to four years in jail.
A total of 6,908 knives were confiscated by the courts in England and Wales in 2014/15 as last year's official figures showed a rise in knife crime for the first time in four years.
Following the verdict, Detective Chief Inspector Chris Jones said: "Stefan Appleton was killed as he socialised with friends at a park in Islington on a summer's evening last June.
"In front of playing children, his attacker struck him with a 'Zombie Killer'-type machete from which Stefan suffered fatal injuries.
"There can be absolutely no excuse for young people to carry such dreadful weapons on London's streets and this case once again highlights the awful consequences of doing so.
"Finally, I would like to thank Stefan's family that have conducted themselves with dignity, demonstrating enormous strength and resolve throughout what must have been a very difficult trial process."
Sentencing was adjourned until April 21.