A pensioner, house-sitting for his brother, died from carbon monoxide poisoning after a computer error meant the property's gas boiler was left off a British Gas service register, an inquest was told.

Retired stock controller Peter Lewis-Griffiths, 66, was found dead in the guest bedroom by the cleaner at his brother's house.

David Lewis-Griffiths, who was on holiday with his wife in Tenerife, had taken out a three-star service contract with British Gas on the gas central heating boiler at his home in North Chailey, near Lewes.

As a result of a computer error, the eight-bedroom property had been left off a list of homes with a valid contract, resulting in service visits being missed, East Sussex coroner Alan Craze said.

The cleaner, Helen Simmons, said in a statement she arrived at the property at 8.45am on April 9, 2002. After going upstairs, Ms Simmons said she knocked on Mr Lewis-Griffiths' bedroom door without receiving a reply and went inside.

She told the jury inquest at Lewes Magistrates' Court: "The curtains were open and the windows were closed. I went in and found Peter lying in bed and he had obviously died."

She added that in all the time she and her parents were at the property, none of them felt unwell.

Consultant histopathologist Dr Neera Patel said a post-mortem examination revealed that Mr Lewis-Griffiths, unmarried and from Notting Hill, west London, died from carbon monoxide poisoning.

The hearing continues.