A 20-year-old man has been jailed for seven years after luring a teenager to a restaurant and repeatedly stabbing him because of a feud over a girl.
Jacob Butchoff, a former pupil at the exclusive Hampstead school, UCS, had arranged a meeting at the Hainenese Buffet in Golders Green Road with love rival, Jonathan Kaae-Mortensen.
Then he stabbed the 18-year-old Persian Jew in the neck, ear, back, shoulder and cheek.
Such was the level of acrimony between the pair, both of whom are Jewish, that guards were summoned to the sentencing at Wood Green Crown Court and the families were told to leave separately.
The friction began in 2007 when Mr Kaae-Mortensen had a relationship with Butchoff's ex-girlfriend.
There had been a previous incident between them, which led to Mr Kaae-Mortensen's family sending him to America for a year.
Butchoff, of Brent Street, Hendon, called Mr Kaae-Mortensen two days before the attack in September, threatening his family if he did not agree to meet.
After 20 minutes in the restaurant, Butchoff drew a knife across his neck before plunging it into his body.
The attack ended when Mr Kaae-Mortensen's father, who had gone with his son for protection, struck Butchoff with a cosh.
Butchoff was stopped by a passing Police Community Support Officer as he fled. As his victim was led to the ambulance, he shouted: "I will kill you. Just wait until I get out."
Dora Belford, defending, said: "Mr Butchoff has a complicated background and being taunted about being adopted by a wealthy family is something that has been aired between the men in the past.
"There was a conversation between the two young men for 20 minutes that shows this wasn't the defendant hot-headedly seeing the victim and immediately attacking him."
She also drew the judge's attention to an incident outside the court moments before the hearing, when Mr Kaae-Mortensen had walked over to the Butchoff family "in an aggressive way," asking them: "Have you said goodbye to your son?" She said this showed the victim "may have provoked matters".
Then Ms Belford read out a letter from Butchoff which said: "I still have not and may not ever forgive myself for acting so disgracefully".
But Judge Fraser Morrison said: "You were armed in advance, having gone to the restaurant with the knife.
"In my judgment it was a premeditated attack. You drew the knife across the neck leading to a gash of blood. The attack only came to an end because of the swift intervention of the victim's father, who had to intervene with significant force."