The small living room on Fernagh Road is bedecked with cards from floor to ceiling. It could be a scene from Christmas only there is no festive cheer in this house.

Instead the room has become a shrine to an only son snatched away by the silent killer that is carbon monoxide poisoning.

The grief-stricken parents of A-level student Aaron Davidson, Katrina and George, sit together in the semi-detached house in Whiteabbey and read the statement issued by a solicitor on behalf of gas fitter George Brown, who is at the centre of the investigation.

At first the devastated mother shook her head grimly and said she had no comment to make.

However, in a courageous gesture of magnanimity in the midst of their grief, Mrs Davidson expressed sympathy for Mr Brown and his family.

“I’m sure he is as devastated as we are about what has happened,” she said.

“We don’t want to incriminate him because that man has a family of his own. We just want the truth known. As far as we are concerned it has happened — we just want to know why and how.”

Her husband, who clutched another bundle of sympathy cards, said they were the only statement he needed.

“We’ve had cards from people in Lurgan we don’t even know and people we met on holiday before Aaron was even born,” Mr Davidson said.

“We’ve had letters of sympathy from the mayors of Belfast, Coleraine and Newtownabbey — it’s been incredible.”

The Davidsons and 23-year-old daughter Nicola are clearly moved by the huge outpouring of sympathy they have received since the tragic deaths of Aaron and life-long friend Neil McFerran last week.

The 18-year-olds, along with friend Matthew Gaw, had been enjoying a holiday at an apartment belonging to Aaron’s aunt in Castlerock.

It was a short break to relax ahead of exam results due next week. Matthew survived, but tragically his pals succumbed to the deadly effects of carbon monoxide, which investigators have found was caused by a defective gas appliance in the Tunnel Brae Court apartment.

The Health and Safety Executive Northern Ireland took the unprecedented step earlier this week of issuing an alert to anyone who had gas work carried out in their home or premises by Mr Brown, of the Calor Shop in Coleraine, to switch off all gas appliances and contact its emergency helpline.

It has not been possible to contact Mr Brown, but yesterday morning he issued a statement expressing “his most sincere condolences to the Davidson and McFerran families following their tragic loss”.

The Castlerock apartment is owned by Mrs Davidson’s sister, Yvonne Best, who had become ill last month after staying there.

The family repeated their call for all premises to be fitted with carbon monoxide alarms.

Mrs Davidson said she wanted to make sure another family doesn’t have to endure the pain she and the McFerran family are going through.

“We have to do something to make sure the boys’ deaths weren’t in vain. If we can save someone else’s child or relative it will be worthwhile.”