A coroner voiced safety concerns over a farm where a 21-year-old student drowned in a grain silo.

Arthur Mason, 21, had climbed inside the silo at Hall Farm, Fincham, near King's Lynn, after he was instructed to clean it with a broom.

He was wearing a harness, but sank under tonnes of wheat.

His colleagues heard his 'muffled shouts' but could not raise his head above the grain, and efforts to use a pipe to help him breath failed.

An inquest jury yesterday concluded that Mr Mason, of Eastmoor, King's Lynn, died accidentally on July 9, 2014.

They stated that he was standing on moving grain when his colleague went to close a hatch at the foot of the silo.

When the colleague returned to the top, Mr Mason was beneath the grain.

Jurors said that limited risk assessments and limited training contributed to the death of Mr Mason.

Paul Unwin, an inspector for the Health and Safety Executive, said standards on the farm appeared reasonable and staff seemed knowledgeable, but had no formal qualifications.

He described the risk assessments that were in place as 'woefully inadequate'.

The harness used to prevent a person from sinking in grain had a shock absorber in its lanyard, designed to prevent injury in a fall from height and meaning it extended from 2m to nearer 3m.

This was the wrong type for the job and defeated its purpose of being as short as possible, Mr Unwin said.

Chris Legg, manager of the farm, said everyone was banned from entering the grain silos the day after the accident.

Staff now cleaned the silos externally using an industrial hoover, though emergency plans had not been reviewed since the incident.

Asked why, Mr Legg said: 'It's something we will get to but we have not at this stage.'

He added: 'It's been the most traumatic thing I've lived through.

'Both me and Hugh [Mason, Arthur's father] were happy for our children to work at the farm, and we will take the guilt and sorrow to the end of our days.'

Senior coroner Jacqueline Lake ordered that reports to prevent future deaths be made in respect of training and emergency planning at farm company Maurice Mason Limited.

She commended the work of emergency services, stating they acted 'swiftly and in very difficult circumstances'.