A Worcester pensioner was put in danger after a local builder and his son knowingly carried out defective gas work while constructing a conservatory at her home.

Christopher Amphlett, 65, and his son Mark, 37, traded as Worcester Windows, Doors and Conservatories. The pair knew they had to manage the existing flue of the gas boiler before they began the conservatory at the property in Hillside Close, but failed to do so.

When they finished the building in the Christmas period of 2011, they illegally inserted a plastic pipe into the original flue and extended it through the conservatory roof of the ground-floor maisonette.

Worcester Magistrates' Court heard yesterday (25 April) that the offence only came to light when British Gas visited the property three months later to do their annual check. They detected a gas leak from the flue in the conservatory and immediately condemned the boiler.

An investigation by the Health & Safety Executive (HSE) found the two men were aware that the flue they put in was defective but had made no attempt to rectify it. Neither were Gas Sage registered engineers.

Christopher Amphlett of Newtown Road, Worcester pleaded guilty to breaching Regulation 8 (1) of the Gas Safety (Installation and Use) Regulations 1998, and was ordered to carry out 150 hours of unpaid community work over 12 months. He was also ordered to pay £2,400 costs.

Mark Amphlett of Canterbury Road, Worcester pleaded guilty to breaching Regulation 3 (3) and Regulation 8 (1) of the Gas Safety (Installation and Use) Regulations 1998. He was also sentenced to 150 hours of unpaid community work over 12 months and ordered to pay £2,400 costs.

Speaking after the hearing, HSE inspector Wai-Kin Liu said: "Christopher and Mark Amphlett knowingly proceeded with an illegal gas fitting task that left the home owner at considerable risk. This case could have been much more serious if the resident had not been due a contracted check by the gas provider.

"Gas appliances may be affected by building works or the modification of premises. A common mistake among some builders and people doing DIY work is that they do not consider the implications of the building work to existing gas appliances.

"This case should serve as a lesson to any builder who is tempted to undertake gas work when not qualified and not registered. Householders should be extra vigilant in checking that any gas work is carried out only by registered engineers."