Christopher Barry, 53, was stabbed to death by a 13-year-old boy after a row outside a block of flats . A 13-year-old boy has been jailed for more than 11 years after pleading guilty to a brutal stabbing making him one of Britain's youngest ever murderers. The boy, who is a member of the notorious Wood Green Gang, pleaded guilty to stabbing 53-year-old Christopher Barry twice in the chest outside his home in Edmonton, north London, on December 14 last year. The teenager, who cannot be named for legal reasons, pulled a knife from his rucksack and stabbed Mr Barry, a builder, as he got into a lift following a row. The Old Bailey heard the boy became enraged when Mr Barry, who was known as Jack, would not let the boy and his friends into the block of flats. Zoe Johnson QC told the court the murder happened on December 14 last year, as the killer attended a 13th birthday party at his friend's flat off The Broadway, in Edmonton, north London. He and a group of friends left the flat to see one boy to his bus home, but returned to the wrong block to try to rejoin the party. 'Tragically it appears they returned to the wrong door of the wrong block', said Ms Johnson. 'When they buzzed the door, they were buzzing the wrong flat which explains why no one answered.' Mr Barry and his girlfriend, Sabrina Finn, arrived home to find the group of boys trying to get into the black of flats when they lived. Ms Johnson said: 'One of those boys was continually pressing the button to be let in. 'Mr Barry and his girlfriend said they couldn't let the boys into the flat if the occupants weren't answering the buzzer. The attack happened as Mr Barry (left) returned home with his girlfriend, council worker Sabrina Finn (right) 'As Mr Barry used his fob to open the main entrance, it appears there was a bit of pushing and shoving between him and the boys. 'Mr Barry and his girlfriend entered the block and walked to the lift. 'The defendant followed Mr Barry into the block, along a short corridor, around a corner, and as Mr Barry stepped into the lift, the defendant stabbed him twice in the chest, in a completely unprovoked and cowardly attack.' One of the boys with the killer told police he had seen his friend 'become angry and take a kitchen knife out of his rucksack.' Another of the boys saw him thrust the knife at Mr Barry and say: 'What are you saying now? What are you saying now?' before swinging the knife at the victim. When they ran from the block of flats, the killer told a friend he had 'just ripped the man's jacket'. The Old Bailey (pictured) heard the boy became enraged when Mr Barry, who was known as Jack, would not let the boy and his friends into the block of flats where he lived. He fatally stabbed Mr Barry twice . Mr Barry did not initially realise he had been stabbed, but found blood on his shirt and when he entered his flat he collapsed. Paramedics found him laying face down in a pool of blood, with a wound in his abdomen and another in his chest. He later died from his injuries. In texts later that night, the boy told a friend: 'I'm going to prison' and posted on Facebook: 'The thing I'm going to miss most when I go pen (penitentiary) is NY gyal (New York Girl).' Ms Johnson said the boy also went by a street name associated with the Wood Green Gang. 'This is a gang that he candidly admitted he was associated with since the age of ten', she said. The court heard the teenager was given a police caution and excluded from his first school when he was caught with a knife and cannabis in February 2013, then aged just 11. Ms Johnson said Mr Barry's girlfriend, Ms Finn, had written an impact statement describing the 'appalling effects on her and many of Mr Barry's family and friends'. 'I'm back at work now, but although I walk, talk, and look the same as I did before, inside I'm tired and my heart is broken', she said. Mr Barry was stabbed following the row outside this block of flats in Edmonton, north London (pictured) 'Jack and I had four happy years together and this young boy has taken that happiness away from me. 'For that I'm very sad and angry as my life will never been the same again.' The boy's mother wept in court as Judge Stephen Kramer QC today sentenced the boy to a minimum of 11 years detention at her majesty's pleasure. 'When Mr Barry returned home, he refused to let you in to that block but you nevertheless got in', he said. 'You followed Mr Barry, produced your knife, and then stabbed him twice in the chest. 'The injury to the chest went through clothing including a wax jacket and went deep.' 'You are only 13 years old but shortly after 7.30pm on the evening of December 14 2014, you were carrying a knife in your bag. 'You wanted to get into a block of flats but you went to the wrong block with tragic consequences for everyone involved.' The judge said it was an aggravating factor that the boy had taken the knife to the scene in his bag and said he had clearly intended to cause really serious harm to Mr Barry. The boy has been deemed a high risk of causing harm and at a medium risk of reoffending when he is released, and the judge urged him to reconsider his gang affiliation. However he also accepted it was not a premeditated attack and that the boy had a 'troubled background'. He took into account the boy's remorse, revealed in a letter from his mother which was not read out in court. The boy, wearing a pale blue shirt with a white buttoned up collar, showed no emotion and stared straight ahead as the sentence was passed. The teenager pleaded guilty to one count of murder on March 6, and Michael Turner QC, defending, said this was a 'unique' early admission from such a young defendant. Judge Kramer refused an application by the press to lift a legal ban on naming the boy, saying there were 'exceptional' circumstances.
A boy aged 13 has been jailed for 11 years for murder of Christopher Barry .
He stabbed Mr Barry, a builder, twice in 'cowardly and unprovoked' attack .
Teenager was a member of the notorious Wood Green Gang in London .
Boy was thrown out of school at 11 for possessing cannabis and a knife .