A man accused of killing a security guard by wrongly fitting a gas heater to his camper van admitted today that he had been "negligent".

Stephen Bratt told Lewes Crown Court he believed he had fitted the propane heater correctly to the Leyland Sherpa van used by a security firm hired by the BBC.

BBC staff filming an episode of Tomorrow's World at Belle Tout lighthouse at Beachy Head near Eastbourne, East Sussex, found the body of security guard Allan Mollison, 43, in the van on March 17, 1999.

He had been employed by BW Security to protect expensive camera equipment overnight.

A post mortem examination found that Mr Mollison, of Nottingham, had suffocated due to carbon monoxide poisoning caused by the heater, installed by Mr Bratt under a bunk bed.

Bratt, of Long Eaton, near Nottingham, had turned the J-registered van into a "mobile gas chamber", said Paul Garlick QC, prosecuting.

He did not have a manual for installing the heater, and did not seek advice from the manufacturer.

Bratt denies the manslaughter of Mr Mollison and an alternative charge of failing to ensure the safety of anyone using the van.

He told the second day of his trial that he had acquired the Propex heater second-hand, and did not tell BW Security chief Michael Burrows that it was not new.

He charged more than £4,000 for converting the van and billed the firm with a receipt headed Stephen Bratt Mobile Conversions, even though he was not a trained fitter or a registered CORGI fitter.

Bratt told the jury: "When I took the van back I thought Mr Burrows would have it checked out, or have it serviced. I presumed he had more knowledge than me."

Mr Garlick told him: "This incident was a result of negligence." Bratt, fighting back tears, replied: "Yes."

The court heard yesterday that BW Security boss Mr Burrows and his co-director Robert White, a former Detective Sergeant, admitted a charge brought by the Health and Safety Executive of exposing employees to risk.

They were fined £2,500 each while the firm was fined £4,000.

The case continues.