The 52-year-old, originally from Cobh, had been living in London since 1983 and worked in construction.
It is understood he was returning from a local bar with his girlfriend, Sabrina Finn, 35, on Sunday evening when he came across a group of teenagers attempting to enter the apartment block where the couple were living in Edmonton in north London.
Following a verbal altercation with the youths, it is understood he received a single fatal stab wound in the back. The emergency services were called but Mr Barry was pronounced dead at the scene shortly after the arrival of medics and police.
A number of youths, all aged between 13 and 14, were arrested in relation to the investigation. Four of the schoolboys were released on bail but a fifth had been detained by police. Last night a 13-year-old boy was charged over the killing.
It is understood the teens had been trying to access a party at another address in the flats complex. As the row escalated, Mr Barry sustained a fatal stab wound after reportedly being followed by two of the gang.
His girlfriend was yesterday being comforted by friends and relatives.
Friends and relatives in his home town, where Mr Barry came from and visited almost every year, paid tribute to the builder, who was described as a “quiet and unassuming” man.
His uncle, Noel Barry, said he was shocked at the brutal stabbing. “As far as I can gather, himself and Sabrina, his partner, went to a local bar at about 5.15pm and returned at about 7.45pm to find a group of young fellas outside the main door of the private block of apartments where they were trying to gain entry. Something happened verbally and, as he went in the door, he was stabbed in the back — one stab wound. He went in, up the lift, and he collapsed in the apartment and she sent for the ambulance services,” he said.
Speaking to RTÉ radio, Mr Barry said his nephew had worked hard since he moved to England in the early 1980s.
“Those young fellas wouldn’t even be going to secondary school and you’d imagine at 8.45pm they’d be at home preparing for school the following day. They shouldn’t be out going to a party at 8.45pm on a winter’s night.
“He was typical Irish. He worked hard and he never lost his Irish accent. He was a plumber but he became a jack of all trades really. He done everything really, tiling, carpentry work, block work, plastering, everything.”
Mr Barry said his nephew usually returned once a year to visit, particularly if an old school friend living in the US was also back in Cobh.
“He’d come on average maybe once a year. He’d usually come with some purpose in mind. He had a great friend, a school friend in America, Michael O’Connor. Michael would come home to visit his mother in Cobh and Jack would usually come across and they’d meet up here in Cobh. Or sometimes, Michael would go on to London and meet him in London.”
Local Sinn Féin councillor Kieran McCarthy, who had known Mr Barry since they were children, said the community was “shocked” by the murder of a man who “never harmed anyone”.
“It was such a shock to hear what happened. He lived in England and was a builder by trade but he was such a quiet an unassuming man that would never have harmed anyone. I would like to offer my sympathies to his family.”