An autistic man found hanged at a ward in Little Plumstead Hospital had been 'extremely positive' about his prospects in the days leading to his death, an inquest has heard.

Philip Sewell had been detained by the state at the time of his death on April 14 last year, having been convicted of an attack on a sex worker in 2011.

The 24-year-old was assessed by clinicians while at HMP Norwich, and it was decided he should be moved to Broadland clinic at Little Plumstead due to his 'poor self care, deficits in communication and significant anxiety.'

While no mental illness was diagnosed, Mr Sewell began to report some 'unusual experiences such as hearing voices,' Norfolk Coroner's Court was told by area coroner Yvonne Blake.

He had been improving significantly since being transferred to hospital in September 2011, and by April of last year had been moved to the Mayflower ward and was preparing for release, potentially by the winter.

Dr Daniel Dalton, consultant forensic psychiatrist at Little Plumstead, told the court he had been 'profoundly shocked' at the death.

Staff had been exploring Mr Sewell's sexual preferences with him to help him understand his conviction, and while there was no explicit reference to erotic asphyxiation they would not rule it out as a possible factor in his death.

'I would not put it beyond the realms of possibility this was an experiment gone wrong,' said Dr Dalton. 'Philip was a very shy man who felt very uncomfortable talking about some things very personal to him. They were very important in understanding the offence.

'He never denied he did what he did, but he struggled to understand the seriousness of what he had done. He was naive from a sexual point of view. He found his sexual thoughts and wishes extremely troubling.' Dr Dalton added since Mr Sewell's death the hospital has changed practices, including ending 'listening' observations. 'It is impossible to take away every possibility someone could use to harm themselves or others,' he said. 'In Philip's case he was doing tremendously well and there were no signs he might be doing anything accidentally dangerous. With hindsight I can't say how much I regret the fact he had the things he needed to harm himself.'

Mr Sewell's mother Jasmine Baker told the court she was '100pc sure this wasn't suicide', as he would often send the family items he considered dangerous for safe keeping.

The inquest, expected to last three days, continues.