Cyrena Barned said outside court that she was pleased with the 31-year sentence received by Dean Smith, for the murder of her brother Aarron McKoy.
Judge Wendy Joseph said it had been said during the trial that Dean Smith had a loaded gun and was "going to shoot someone".
Cyreena McKoy said the murder had devastated her family. Her brother Lee was "like a lost soul" without his twin.
"Dean Smith had no reason to commit this senseless act," she said in a statement.
The court heard that Mr McKoy became the innocent victim of a long-running feud between two gangs.
He had had friends who were associated with the Holly Street Boys, while Smith was a long-standing member of the rival Lordship Lane Boys.
He arrived with a group at the Clerkenwell House wine bar in central London as Mr McKoy and his friends were peacefully celebrating.
A gunman was today jailed for a minimum 31 years for killing a teacher's son celebrating his birthday in a wine bar.
Aarron McKoy was with his twin brother Lee and it was their 22nd birthday in the early hours of New Year's Day when he was shot three times.
Dean Smith, 26, of Stoke Newington, north London, was found guilty of murder at the Old Bailey last week. He was jailed for life and told he would serve a minimum of 31 years.
It was a true execution of a young man who was utterly defenceless and at your mercy.
Aaron had done nothing to you or indeed anyone else.
A gunman is today facing a life sentence for killing a man celebrating his birthday in a wine bar.Read the full story ›
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A family escaped the flames of their burning home in Stoke Newington yesterday thanks to the quick-thinking, and bravery, of passers-by.
One of the heroes climbed a ladder to rescue three children, their father and their nanny from the fire.
Timo Dobrowolski said he called on the training he received in a fire brigade youth group in Germany when he was a boy.
Carolyn Sim has the story.
Helen Johnston, an aid worker freed in Afghanistan, was taken hostage along with three others in Badakhshan province on May 22.
We are delighted and hugely relieved by the wonderful news that Helen and all her colleagues have been freed. We are deeply grateful to everyone involved in her rescue, to those who worked tirelessly on her behalf, and to family and friends for their love, prayers and support over the last twelve days.
David Cameron spoke of his relief earlier at the news that a rescue attempt to free Helen Johnston, an aid worker from Stoke Newington captured by the Taliban, had been successful
Aid worker Helen Johnston from Stoke Newington has been rescued in a military operation after being kidnapped in Afghanistan.Read the full story ›