16-year-old Harry Pitman was stabbed to death on Primrose Hill by another teenager when New Year “revelry” turned to violence.Pitman collapsed and died “almost immediately” after being stabbed in the neck on New Year’s Eve last year while enjoying a night out with friends.Another teenager, 17, has admitted inflicting the fatal wound and is now on trial for murder.Jurors have been told the teenager on trial for murder admits stabbing Harry, but is set to argue he was acting in self-defence.The suspected killer was himself 16-years-old at the time, and cannot be identified due to his age.