A public schoolboy who stabbed his best friend 13 times and left him for dead "for his own personal gratification" was locked up for nine years today.
Harry Schick, 17, tried to kill 16-year-old Gavin Doyle after luring him to darkened woodland, the Old Bailey heard.
The teenagers were both A-level students at the £14,000-a-year Pangbourne College in Berkshire.
Gavin, who hoped to become a Royal Marine, had paid Schick £400 to get him a Pioneer air pistol which he wanted for target practice but was too young to buy.
The victim, from Surrey, arranged to meet Schick so he could hand over the weapon in Lloyd Park, Croydon, late at night in March.
But as he had his back turned the older boy produced a large knife, stabbing him repeatedly during an hour-long attack.
Schick took his victim's mobile phone and deleted records of contacts between the two, before tossing it onto his chest where he lay on the ground.
Gavin suffered a pierced liver and a collapsed lung and could have died but managed to use the handset to dial 999.
Schick, of Kenway Road, Earls Court, west London, at first denied anything to do with the attack but pleaded guilty to attempted murder as he was due to go on trial last month.
Judge Richard Hawkins told the boy that the stabbing had a "traumatic" effect on the victim - who is now 17 - adding: "What makes it worse is that he considered you as a friend."
He ordered a further psychological assessment once Schick had served his sentence after a report found that while the defendant presented a "low to medium risk of future violence", it was a "very unusual" attack.
Detective Sergeant Tim Hammond said: "He is a strange character and I think a very dangerous character.
"We have got nothing to suggest any motive other than he wanted to kill the victim for his own personal gratification."
The judge declined to ban the young defendant from being identified, saying: "In view of the gravity of this case the press ought to be free to report it."
Schick, an only child whose mother is estranged from his US-based father, looked close to tears as he was sentenced.
As he was taken down, a male voice shouted from the public gallery: "Enjoy it you f****** c***."
The judge had been handed a letter from Schick's mother and another from the defendant himself, in which he apologised for the attack.
His mother wrote of her shock at the actions of her "popular" son who "everyone thought well of" and who had won a school award for his consideration to others.
"What has happened is so tragic and incomprehensible," she said.
Benjamin Squirrell, defending, said: "It is clear that this is a tragic case, not only for the defendant but also of course for the victim.
"It is very difficult throughout all of the reports and letters to find any underlying reason to make it understandable.
"It is clear that the defendant was not suffering from a mental illness at the time but perhaps there is something in what his mother says in the letter, that he had effectively become distanced from reality.
"He had been living in a different world, detached from his feelings.
"Perhaps that is one reason to understand how someone who had so much to offer, who was doing so well, who had not displayed any of these tendencies or behaviour, would choose to attack one of his best friends.
"It obviously goes beyond anyone's comprehension.
"He has no previous convictions or history of violence and psychiatrists described this attack as surprising in the context of an individual who has no known history of aggression or violence.
"It is unlikely that this set of circumstances will ever arise again."
The judge told Schick: "You made it clear during this hour-long attack what your intention was - to kill him.
"You got a SIM card specially to contact the victim days before the attack. You took a knife out to meet him in a lonely place, changing your clothing.
"The attack was on a close friend and it was sustained, over an hour, and the victim has suffered psychologically and physically to a serious extent."
The judge told Schick that had Gavin not been able to call for help, he would have been facing a charge of murder.
He was discovered covered in blood and spent three days in intensive care.
Gavin suffered wounds all over his body - including defensive injuries to his fingers as he tried to ward off the attack that may damage his ambitions of joining the Marines, the court heard.
Det Sgt Hammond said: "This was a horrific and still apparently motiveless attack on a 16-year-old boy at the hands of someone he trusted as a close friend. It was a cold and calculated crime that the attacker had been planning for some time.
"The victim would almost certainly have died had it not been for the quick response of the police and the London Ambulance Service."