A feared gang member who once led a reign of terror at a Streatham secondary school has been convicted of murder.

The 17-year-old, who cannot be named for legal reasons, was found guilty on Wednesday of stabbing 29-year-old Orlando Thompson to death.

The murder in June 2007 took place two years after the teen was given a 42-month sentence for viciously robbing children from Bishop Thomas Grant School, in Belltrees Grove, with an accomplice.

The pair picked on so many children, lining them up against a playground wall to rob them, police had to send a minibus to transport their victims to an identification parade.

Mr Thompson was stabbed twice in the chest with a 12-inch kitchen knife after he stepped in to protect his girlfriend during a row in a children's play area in the Kennington Park Estate. He died a few hours later in hospital - days before his first child's christening.

The Old Bailey heard how the teen, from the Kennington Park Estate, held a grudge against Mr Thompson's girlfriend's brother, believing he had "snitched on him" to police over a hidden shotgun.

On June 15 the boy spotted the girl in the play area on the estate and slapped her across the face.

Mr Thompson then confronted the teen. One of the boy's friends punched him to the ground, leaving him defenceless, before the defendant stabbed him in the chest.

The teen will be sentenced for murder on March 7.

In 2005 he and a friend, neither of who attended Bishop Thomas Grant, were jailed for terrorising the school's pupils, violently frisking them for valuables.

One 16-year-old victim needed hospital treatment after being punched and kicked and another boy's jaw was broken by a blow to the face.

The pair posted lurid details of the robberies on a gang website and wrote rap lyrics about their exploits.

The judge at the time told them their "reign of terror" had led pupils to think violence was a normal part of school culture.