An airport company has been convicted of health and safety breaches which led to the death of its chief fire officer, Steven Mills, 45, of Malmesbury.

Mr Mills was killed on April 8, 2011, when a giant gas cylinder suddenly discharged and hit him on the head as he was moving it at Cotswold Airport - the former RAF Kemble site near Cirencester, Gloucestershire.

The army surplus cylinder had been designed to pump a heavy gas into a sprinkler system if fire broke out in areas where electronic equipment was used, Gloucester crown court was told.

It was one of many which had been in use in Iraq but had been shipped back to the army storage depot at Ashchurch.

The cylinders and their containers were then offered free of charge to the airport company and had stood disused at Cotswold Airport for several months before the day of the tragedy.

The prosecution said the airport company had not properly assessed the risks of the cylinders or the way they were stored.

There had been no assessment, either, of how the five foot high cylinders should be safely moved, the court was told.

Kemble Air Services Ltd pleaded not guilty to failing to make suitable and sufficient risk assessments of the danger to both employees and non employees at the aerodrome on April 7, 2011.

But after a six-day trial a jury of 11 found the firm guilty of both charges yesterday.

Judge William Hart adjourned sentencing until a date to be fixed after telling the jurors that the penalty would be a fine.

He said he was adjourning to give prosecution and defence to make submissions about the appropriate penalty.

He said: “My sympathy goes out to the partner and family of Mr Mills.”

Prosecutor Simon Morgan said he would in due course be applying for the company to pay the trial costs of £104,085.

He handed the judge victim impact statements from the wife, parents and sister of Mr Mills but did not read them aloud in court.

Before adjourning Judge Hart asked the prosecutor to pass on his sympathies to Mr Mills' family.

"These are important cases when they involved someone's death and it is alleged to have been due in part to a criminal offence," the judge told the jury.

At the start of the trial Mr Morgan had alleged the company's health and safety policy was 'deficient and you may think wholly inadequate.'

There was nothing at the airport to tell Mr Mills how to move the cylinder safely, and nothing to identify the hazards of the gas inside, he said.

Defence barrister James Maxwell-Scott had asked the jury to find that there was no reason why the company should have prepared a risk assessment of the gas cylinders at the time that Mr Mills was killed.

The company had no plans for the cylinders at that time and did not know that Mr Mills, an experienced and highly trained firefighter, was going to do anything with them on the day he died, said Mr Maxwell-Scott.

Mr Mills worked on the family farm in Minety and was also a retained firefighter in Malmesbury.

After the hearing, his father Alan, speaking on behalf of himself, his wife Marie, and Steven’s brother and sister, said: “His attitude was perfection in anything he undertook to complete.

“No individual person is responsible for the death of my son. It was a series of minor irregularities, leading up to a major event resulting in accident.

“Nobody made a desperately bad mistake.

“Steve’s death came as a bitter blow. He was a popular person.

“He was not only my son, but a good companion.

“He had many interests in life and worked hard.

“After his retirement as a firefighter, he planned to run the family farm in partnership with his brother Andrew.

"Time is a good healer, but Steven will be sorely missed for many years to come.”

A four-day inquest in 2012 concluded that Mr Mills’ death was accidental.