A lack of staff experience and a failure to follow protocols contributed to the death of a teenage boy who drowned at a west Norfolk beauty spot, an inquest has heard.

Umar Balogun, 16, died at Bawsey Pits, near King's Lynn, on July 16, 2013, while on a day trip with support workers from Castle Lodge care home, in Cambridgeshire, where he was living.

During a four-day inquest at Norfolk Coroner's Court, jurors heard how a risk assessment completed when Umar moved to the home, which closed in August 2013, said he was at high-risk for swimming and that he should only do so when lifeguards were present.

But the manager of the care home, Lyana Sinclair-Russell, did not read the assessment before the trip and did not check where the party were going.

Earlier in the week she accepted that it had not occurred to her to check whether there would be lifeguards. 'Had I known it was not an appropriate seting it would definitely not have gone ahead,' she said.

The jury yesterday returned a verdict of accidental death, noting a lack of staff and training and experience, that policies and procedures were not implemented and that protocols were not adhered to prior to the trip and at the site.

The court heard how the two care workers, Vanda Cawley and Kevin Roweth, took Umar and fellow care home resident Jamie Whiteman to the former quarry and sat on the shore while the boys paddled and waded into the water, near to 'no swimming' signs.

Summing up the evidence, coroner for Norfolk Jacqueline Lake said: 'The boys continued into the water until they were waist deep and were splashing each other. They started ducking under the water two or three times until Umar went under and did not come back up.'

A search began, and Umar's body was discovered entangled in what diver Alan Nicholls, of Norfolk Fire and Rescue Service, described as a 'weed forest'.

The inquest heard how Mr Roweth had been at the care home for just three weeks before the tragedy, and Miss Cawley had not yet passed her six-month probation period.

Both Mr Roweth and Miss Cawley are being investigated by the Health and Safety Executive.

Yesterday Mrs Lake confirmed that she would not be filing a prevention of future deaths report against Castlecare Ltd, who owned the care home, and Sibelco, who own Bawsey Pits.

She said: 'I sincerely hope that following this inquest that members of the public seriously think about entering those lakes however attractive and benign they seem.'

She added that there was a 'number of issues and concerns' about Castlecare but said she was satisfied 'the company have looked at and scrutinised their procedures'.

A charge of corporate manslaughter against Castle Homes and gross negligence manslaughter against staff members Miss Cawley, Mr Roweth and former care home manager Lyana Sinclair-Russell had been considered but did not meet the threshold.

Internal disciplinary action was taken against those members of staff. Miss Cawley later resigned and Mr Roweth and Ms Sinclair-Russell were dismissed.

Another man died at the site on the same day. Ryan Pettengell, 41, from King's Lynn, was recovered from a separate pit.

Swimming is banned there because of dangerous weeds growing below the surface.