A 16-year-old was ordered to be detained for seven years today for a "disgraceful and brutal" attack on another boy in a park.
William Hutson was 15 when he was with a gang who left the teenager with brain damage after punching him to the ground and stamping on his head.
The victim had been with a friend in Blagdon Park, Malden, Surrey, in April last year when the gang stole a mobile phone headset from them.
Old Bailey Judge Christopher Moss told Hutson: "The sentence must reflect the shocking gravity of your violent and brutal behaviour.
"Your part in this disgraceful and brutal attack, I am satisfied, was that you stamped on his head."
The judge said the victim had decided to stand up to the gang but was knocked to the ground and kicked.
He was taken to hospital but was unconscious for 16 days. He suffered brain damage from which he was slowly recovering, although he would never fully recover, said the judge.
Hutson, of Mitcham, south London, was found guilty last month of causing grievous bodily harm with intent.