Steven Grisales died after he challenged youths who were throwing conkers at him (Metropolitan Police/PA)
A teenager who stabbed a student to death in a row over conkers has had his sentence increased by the Court of Appeal.
Sixteen-year-old Ochaine Williams - who can be named for the first time - was in the dock at the London courtroom to hear three judges increase his minimum term from 10-and-a-half years to 12 years.
Williams, of Victoria Road, Edmonton, north London, was 15 when he killed architecture student Steven Grisales after he challenged youths who were throwing conkers in their spiky husks at him.
Mr Grisales, 21, had been shopping for his grandmother and was on his way to Silver Street station in Edmonton when he was attacked in College Close in August 2011.
Williams denied being the killer, but was found guilty of murder at the Old Bailey earlier this year.
Judge Richard Marks ordered him to be detained at Her Majesty's Pleasure, with the minimum term of 10-and-a-half years.
But at the Court of Appeal, Lady Justice Hallett and two other judges agreed with submissions made on behalf of Attorney General Dominic Grieve that the original minimum term was "unduly lenient".
Lady Justice Hallett, when increasing the sentence, said: "This was yet another example of mindless violence on the streets of London.
"Mr Grisales, an innocent young man, has died simply because he dared to stand up to bullies."
The court heard that Williams has made an application for leave to appeal against his conviction. An order suspending publication of his name pending an appeal was lifted by the three judges following a media application.