The father of a farm worker who was killed in a trailer crash has told a jury he was ‘grinning like a Cheshire cat’ just minutes before the accident.

James Dorman was working with his son Kevin at a farm in East Devon when his tractor and trailer went out of control and plunged down a 16ft bank into a sunken lane.

Mr Dorman told Exeter Crown Court he did not see the accident but had passed his son in the field as they were both moving loads of silage.

Kevin Dorman, aged 25, died from head injuries after being trapped in the cab of his tractor by the ten ton weight of the trailer, which fell onto it.

Farm manager George Perrott and the farming arm of Clinton Devon Estates are on trial accused of manslaughter and health and safety offences arising from the accident which happened at Houghton Farm, Newton Poppleford, on May 19, 2014.

The prosecution say the accident was caused by the total failure of the brakes on the trailer. They say Mr Perrott failed to maintain it properly and the company failed to put safe systems of work in place.

The jury has been told the weight of the trailer, which was half full of silage, caused Kevin to lose control and forced both vehicles through the hedge at the bottom of the steeply sloping field.

Mr Dorman, who is known as Jim, said he was aware there had been a problem with the brakes on the trailer his son was using and he had seen it with its wheels off the day before the tragedy.

He said Kevin was an experienced tractor driver who had worked on farms since he was a schoolboy and had been employed by Clinton Devon Farms for a year before his death.

Mr Dorman said another farm worker had raised concerns the previous week about the brakes on the Richard Western trailer, which his son was using.

He said: “I think I was told that on the Thursday or Friday, May 15 or 16. We were still using it but not on steep ground. I can remember the trailer being parked in a shed over the weekend with its wheels off.”

He said on the day of the accident, he was driving one tractor and trailer and his son was driving another. They were picking up grass cuttings but the fields were wet because of a violent thunder storm.

The conditions were so slippery that he had been unable to get up a field with a full load in his trailer.

He said: “I passed Kevin as I was taking my first load to the silage clamp. He seemed very happy. He was smiling like a Cheshire cat and everything seemed to be going all right. When I returned I was told what had happened.”

Another tractor driver, Andrew Turton, said he passed Kevin just before the crash and saw no signs of worry or panic. He said: “I could see him in my mirrors and eventually he wasn’t there any more.

“I did not think there was a problem before it happened. He disappeared and there was an almighty bang so I stopped and went to help.”

Former firefighter Mr Turton said he saw Kevin trapped in the tractor but could feel no pulse. He told the emergency services in a 999 call that they would need heavy lifting gear to free him.

He said he had reported a fault in the brakes of the Richard Western trailer the previous week but they had been repaired and he found them improved when he next used it.

Kevin’s fiancée, Kirsty Clode, told the jury in a statement that they were buying their first home together on a joint ownership scheme and were planning their marriage when he died.

Perrott, aged 51, of Colebrook, Crediton, denies gross negligence manslaughter and Clinton Devon Farms Partnership, (CDFP) of Hawkerland Road, Colaton Raleigh, deny corporate manslaughter. Both deny failing to ensure the safety of an employee.

Earlier, the prosecution concluded its opening by alleging that Kevin died because the farm company failed for enforce its own safety rules.

Clinton Devon Farms Partnership is a division of Clinton Devon Estates which manages 2,800 acres of organic farmland in the Lower Otter valley.

Clinton Devon Estates is Devon’s biggest private landowner with 17,000 acres in East and North Devon and 350 houses. It manages the holdings of Lord Clinton.

Mr Simon Laws, QC, prosecuting, said the brakes on the Richard Western trailer which Mr Dorman was towing failed completely and led to him losing control and crashing.

He said it was Mr Perrott’s job to maintain the trailer but checks after the crash showed the brakes had not been tightened correctly and the work had been ‘dreadful’.

Mr Laws said the company did not have the systems in place to ensure regular and efficient work was carried out and the only manual dated back to 1994, and was ‘hopelessly out of date’.

He said: “There was a simple failure to engage with reality and run the business in a way that did not put workers’ lives at risk through a lack of basic maintenance.

“Nobody either internally or externally had any proper oversight of Mr Perrott’s work so the trailers were neglected to the extent that one did not have any brakes at all.

“Our case is that this breach is so bad, it amounts to a crime. You might think it is a basic and vital step to check if the brakes were working after they had been adjusted.

“That cannot have been done or the problem would have been discovered. To allow a trailer in this condition to be used by an unsuspecting driver is grossly negligent.

“There is no suggestion that Mr Perrott intended this outcome but what he did was exceptionally bad and therefore a crime. The case against CDFP is that no system was in place to ensure maintenance was carried out to a reasonable standard.

“The failure by senior management was extremely serious. A man died because no steps were taken to ensure he was driving a safe trailer.

“They had written policies to ensure safety but they were in a filing cabinet somewhere and not applied on the ground. Having systems is one thing and making sure they are implemented is quite another thing. It was simply a paper exercise.”

He said police arranged to check the brakes on the other two trailers in use on the farm but arrived to find that they had been serviced in the day between organising the visit and carrying out the inspection.

Mr Laws said it was apparent that work had been done on the brakes of the two Bailey trailers before police experts had a chance to examine them.

The trial continues.