A boiler which exploded and killed a grandmother was de- commissioned in a "slipshod fashion" by a poorly qualified plumber, an inquest heard yesterday.

Christine Goodall, 65, died of multiple injuries when the cast iron boiler behind the fireplace in her lounge burst, showering the room with shrapnel and burning logs.

Since the explosion, Severn Vale Housing Association has visited about 1,700 homes to make sure residents are safe.

Mrs Goodall, a retired shop assistant, was told the open fire in her home at Twyning was safe to use when the boiler was put out of service in 1999. After lighting the fire on November 11 last year for the first time since the boiler was put out of service, the boiler heated up, the inquest heard.

Because it had not been fitted with a venting valve, the residual water expanded to bursting point.

Before recording a narrative verdict, Gloucestershire coroner Alan Crickmore said inadequate guidelines provided by Severn Vale, and heating engineer Matthew Lee's lack of understanding, left Mrs Goodall at risk.

Summing up the evidence, he said: "The back boiler was decommissioned by Matthew Lee in 1999, for a contract from Severn Vale Housing.

"While there's no evidence Severn Vale had cause to criticise Mr Lee's work, there's equally no evidence to suggest his work was inspected.

"It seems to me Mr Lee carried out his work in relation to the decommissioning in a slipshod fashion and this, coupled with Mr Lee's lack of understanding of the requirements, led to Mrs Goodall being left in danger."

Earlier in the inquest Mrs Goodall's son Mark Goodall broke down in tears as he recalled the day of his mother's death. He said: "I was shocked at the state of the place. It was totally unexpected. I was happy the boiler was safe – from what my mum was told."

Laurence Aston, contracts manager at Severn Vale Housing Association, told the inquest at Shire Hall, Gloucester, he was pleased with work completed in the past by M & T Plumbing.

He said he understood the work completed at Mrs Goodall's home was not inspected, but this was not unusual as only a selection of homes were visited.

Mrs Goodall had lived in Twyning for 48 years and worked in the Village Stores for 30 years before retiring in February 2007. Her husband Gordon died in 1990 and some years afterwards she found companionship with a new partner Bill, who died died five years ago.

She left three sons, Kevin, 48, Guy, 43, and Mark, 40, and three grandchildren, Aimee, Sebastian, Rory and Laura.

Mark, from Ashchurch, said: "Everyone in the village knew her." His wife Alison added there was no point in criticising the plumber. She said: "He's got enough on his plate. The strongest thing that can come out of this is that people, even in private houses, should get their back boiler drilled or taken out by a competent plumber."

A Severn Vale spokesman said it offered profound sympathy to Mrs Goodall's family: "As a result we have visited around 1,700 of our homes in order to make sure our residents are safe. Customers who may still be unsure whether they have a back boiler, or have a back boiler and are unsure if it is safe, should call us on 01684 272727."