A little bit of care taken during work carried out on a gas heating system would have prevented the deaths of two teenage friends by carbon monoxide poisoning, a judge said.
Neil McFerran and Aaron Davidson – both 18 – were overcome by carbon monoxide fumes at a Castlerock apartment on August 3, 2010.
They were found by their parents, who raced to the seaside village when they were unable to contact the teenagers.
George Brown, whose gas firm had carried out work to the apartment's heating system, admitted his guilt in the manslaughter of the teens in January, as well as a catalogue of other offences.
The parents of both teenagers were present in court for the pre-sentence hearing. The victims had been staying at an apartment owned by a relative when they were overcome by deadly fumes.
Part of the flue from the new gas boiler installed by Brown's firm became dislodged and filled the flat with the odourless killer.
Mr Justice Weir said: "This was characterised by shoddy, dangerous workmanship and this man presided over it." He said far more people could have died, as Brown was responsible for many other gas installations in the area. "This matter is an unmitigated tragedy for everyone and it could so easily have been avoided with a little bit of care," Mr Justice Weir said yesterday.
Brown pleaded guilty earlier this year to the series of offences, having consistently denied any wrongdoing previously.
His admission – marking the first conviction of its kind in Northern Ireland – came just a week before he was due to stand trial.
The 52-year-old, from Ballygawley Road, Aghadowey, had initially pleaded not guilty to manslaughter.
The former owner of The Calor Shop in Coleraine also denied a further 19 charges relating to breaches of health and safety legislation.
However, at Laganside Court in January he pleaded guilty to all 21, including the manslaughter of the former Glengormley High School prefects.
Yesterday the court was also told Brown's two grown-up sons had left the north coast as a result of the double tragedy.
A defence barrister said as soon as he learned of the deaths, Brown closed the gas business, which has remained shut since. He was released on continuing bail and will be sentenced next week.
A spokesman for Calor Gas said: "In the case of George Brown, who was trading as The Calor Shop, Coleraine, Mr Brown's business was a separate legal entity from Calor Gas NI Ltd."