A Bristol teenager who died when he was caught in a farm machine was working alone on a two-man job, a court heard.

Lee Harvey told Bristol Crown Court 17-year-old Lee Mason was operating a soil sifting machine which he thought required two people.

It is claimed that Lee, who was a trainee ground worker for R E Hill & Son in Dundry, was left in sole charge of the device and without the safety guard in place, became trapped and was pulled towards the framework, crushing his neck.

Farm owner Roy Hill, 66, and his son Michael, 32, both deny manslaughter by gross negligence in April 2007.

The pair also deny breaching health and safety rules, but Roy Hill has admitted a separate health and safety charge in employing Lee without carrying out a risk assessment.

Mr Harvey told the court he looked upon his boss as Michael Hill as he gave out instructions and was involved with recruitment.

There was no safety officer at Hill's, Mr Harvey said, and he was unaware of any health and safety system.

He told the court: "Lee could be hard work. You normally had to explain how to do something several times.

"Once he got the hang of something he was good, it would stay in his head and he would proceed with the job."

Mr Harvey said he was given no instructions on how to operate the farm's soil sifting machine, which sieved rough earth into topsoil, and it was just a case of look and learn.

He told the jury that though he never worked on either the old or newly acquired machine, it was a two-man job.

He said: "I was aware Lee worked on his own all day.

"I didn't speak to either of the Hills about that.

"On several occasions I saw the safety guard off when the machine was not being used. The guard was awkward and heavy and Lee wouldn't have been able to move it."

Mr Harvey went on to tell the court that he had seen colleague Colin Blowen and Lee operating the newly acquired soil sifter without the safety guard on before the accident and on the day of the accident he was told Mr Blowen had overheard another employee telling Lee to clean off the belt of the machine.

David Payne told the court he took Lee under his wing and he was a "good kiddy".

Mr Payne said: "I gave him instructions before we used a new cement mixer and we never had any problem.

"I was there with him to make sure he did it okay.

"He was always there on time, he always did as he was told and he was a good worker."

Mr Payne confirmed he was given no written instructions on the soil sifter but had been told to check its oil and diesel levels and grease its rollers in the morning.

Chris Vowles told the court he had worked with Lee and had liked him.

He told the court: "I wouldn't have let him personally on machines, he was young."

Mr Vowles told the court on the day of the accident Colin Blowen had told him another employee had told Lee to make sure something was cleaned off.

Lee Willcox told the Court Lee was a quiet person but he did what he was asked to do and was all right.

Mr Willcox said he had been shown how to use a lorry at Hills and his work there necessitated common sense.

Dr Hugh White, a Home Office pathologist, conducted a post mortem on Lee, from Knowle, who was 5 ft 5ins tall and weighed just 7st 6lbs.

He concluded cause of death was compression of the neck.

On Friday the six men and six women on the jury are being taken to the scene of Lee's death for a site visit.

The case continues at Bristol Crown Court.