'This could have killed you – you have been living on a timebomb.'

David Green and his partner Michael Bushby live in a leasehold flat in Donald Hall Road, Brighton, where subcontractor Mears cladded over a vent for a combined gas fire and back boiler.

The work meant the potentially fatal fumes could have engulfed the couple's lounge and emergency checks were due to be carried out on other properties yesterday.

After gas engineers spotted the error, Brighton and Hove City Council ordered Mears to drill through the cladding on Monday. Now the council is urging anyone with similar concerns to arrange a gas safety check because it is unclear how many leasehold properties could be affected.

Mr Green told The Argus the mistake was spotted when British Gas visited to carry out an annual safety check and said the boiler was in full working order.

He said: "But then they checked the ventilation and it was cladded up. They said, 'This could have killed you – you have been living on a timebomb.'"

The 50-year-old said he has reported the council, which is the flat's freeholder, to the Health and Safety Executive.

British Gas told him he was lucky he had a carbon monoxide detector and refused to allow the appliance to be turned on. Mr Green was given temporary heaters by the council.

Mr Green said other flats in the block may have been affected by the cladding and that other blocks on the Bristol estate have all had their vents covered over.

A spokesperson for Mears said: "Mears carried out a large external cladding scheme at the Bristol Estate in 2014/15. The responsibility for re-commissioning and signing off the heating systems in these properties lay with the council's gas contractor responsible for this part of the city. Mears is continuing to work with the council and its gas contractor to fully investigate this issue."

The council did not confirm who their gas contractor was yesterday.

But a council spokeswoman said they responded immediately as soon as they were advised of the problem, visiting the their health and safety team and representatives from Mears.

She said: "There are no back boilers remaining in council-owned properties on the Bristol Estate and all our tenants receive regular boiler servicing and an annual gas safety check as part of their tenancy.

"We are not aware of any other back boilers in leasehold properties but would urge anyone with any concerns to arrange a gas safety check.

"We take our responsibilities as freeholder (to leaseholders) and landlord (to our tenants) very seriously and are working with Mears to investigate what happened in this case.

"We have also asked Mears to check the external cladding on all the properties, and visit the small number of leasehold homes, to ensure there any no other similar issues."

The council expected these checks to be completed yesterday (Tuesday).

HEALTH ISSUES BEGAN AFTER INSULATION WORK

DAVID GREEN and his partner have been feeling a bit groggy for the past two years.

Mr Green, who lives in a leasehold flat in Donald Hall Road, Brighton, suffers from bad headaches and tiredness while his partner, Michael Bushby, was diagnosed with asthma.

Two years ago Mears, a contractor of freeholder Brighton and Hove City Council, cladded the outside of Mr Green’s block in a bid to insulate it.

It was only when British Gas visited Mr Green last week to carry out an annual service check on the gas fire and back boiler in his living room that engineers saw how a vent in the wall had been blocked off by the cladding.

The vent ensured adequate air was supplied to the boiler for correct combustion, and also allowed outgoing gases to dissipate.

The error meant Mr Green and his partner could have been exposed to potentially fatal carbon monoxide fumes from the boiler.

Mr Green said: “My partner and I have both had health problems over the past two years.

“Michael has asthma, diagnosed since the cladding, and I have had bad headaches and tiredness over the past two years.

“It might not be because of carbon monoxide but it goes back to when the building was cladded. We are both social care workers and this situation is seriously affecting our work and general health and wellbeing.”

He said a British Gas engineer had told him he was “living on a timebomb” and ordered him to stop using the gas fire, meaning the couple had no heating.

The council came and drilled a hole in the wall, putting in a new vent.

While Mr Green may take a while to start feeling better, he was quick to warn others. He said: “There could be people out there with this sort of appliance. I feel this could have been fatal and I insist the council look at why it was cladded over, why it was signed off as acceptable work and a full investigation into whether anyone else could have this sort of system. It’s horrendous.”