A father and son have been cleared of the manslaughter of a teenager who was crushed to death on their North Somerset farm.

But a jury found the owners of Bridgwater Farm in Dundry guilty of health and safety offences for leaving 17-year-old Lee Mason alone to operate a soil-sifting machine with its safety guard removed.

Bristol Crown Court heard Lee’s left arm became caught in the device and he was dragged into its framework and his neck was crushed.

Farm owner Roy Hill, aged 66, and his son Michael, 32, had both denied manslaughter by gross negligence.

The pair also denied breaching health and safety rules in that they failed to provide Lee, of Lisburn Road, Knowle West, with training and supervision to use the machine.

On Thursday a jury of six men and six women took three-and-a-half hours to return not guilty verdicts on the manslaughter charges but found the Hills guilty of the health and safety offences.

Roy Hill had also previously admitted a separate health and safety charge in employing Lee without carrying out a risk assessment.

As she left court Lee’s mother, 41-year-old Jenny Mason, told the Post: “I feel sick, upset, and let down.”

Earlier she had told the Post how Lee, the eldest of her four sons, had loved the job and worked hard to keep it after Michael Hill had raised concerns over his work.

She said: “He loved machinery and anything which had an engine.”

Both Roy and Michael Hill refused to comment as they left court.

The jury was told Lee was just three weeks short of his 18th birthday when the accident occurred.

Philip Mott QC, prosecuting, said he needed things to be explained to him over and over again and he lacked any common sense or instinct about danger, in particular working with machinery.

He told the court: “At the same time, he loved machinery and driving diggers and that was a toxic combination which meant it was probably the last place he should have been asked to work.”

Mr Mott said Hill and Son had no health and safety policy, training courses or risk assessment.

He said it was up to employees to use their common sense to stay safe but, due to Lee’s youth and inexperience, he was not able to look after himself.

The working of the machine which Lee was left to operate was explained to the jury, who went on a site visit to view the machine.

It was used to break up rough clods of earth into topsoil, operated with a conveyer belt on rollers.

The jury, which was taken on a site visit to view the machine last Friday, was told a safety guard was not in place or correctly mounted at the time of Lee’s death.

It was said that Lee, who weighed only seven-and-a-half stone, would not have been capable of removing or lifting off the guard, which weighed five-and-a-half stone.

The prosecution’s case was someone had taken off that guard and for some reason unknown Lee must have put his arm in the machine, become trapped and was pulled towards it.

Though Roy Hill did not give evidence, he told police in interviews after his arrest that Lee was “a good little worker” who was improving.

Michael Hill, said to be heartbroken by the tragedy, said he had made it clear to Lee that the machine should not be operated without the safety guard in place.

The Hills now face an unlimited fine for the health and safety breaches.

Trial judge Mr Justice Jack asked for information regarding their personal and business finances ahead of their return to court on Friday to be sentenced.