The former chief executive of a special hospital at the centre of drug, pornography and sexual abuse allegations admitted last week that she had no experience of patients with psychopathic disorders.

Janice Miles told an inquiry that when she took the job at Ashworth special hospital on Merseyside in July 1993, she had experience in mental illness and learning disabilities, but none involving treating people with personality disorders, also known as psychopaths. But as soon as she started, she restructured the wards so all the PD patients were treated in the same unit.

Ms Miles told the London inquiry, set up by the Department of Health: 'Some people said we were very brave to put PD patients together. I don't think anyone could have done anything else - there was no other choice at the time.

'When I started at the hospital I didn't have the expertise with psychopathic disorder patients. It was only when they were split up more that I realised the complex nature of psychopathic disorders.'

Ms Miles was suspended from the hospital in February last year after allegations about activities in the PD unit. She later resigned. It is claimed an eight-year-old girl was allowed to play unsupervised with a sex offender at the unit and pornography, drugs and alcohol were available on the ward.

The inquiry heard that when Ms Miles started at the hospital she introduced a 'devolved' management structure. Managers took responsibility for the day-to-day running of the four new units, but overall control came from above.

This caused tension among staff, including some in senior positions, but Ms Miles refused to name names. She said: 'For some staff life had been easy, and we were putting on pressure to improve clinical practice and adopt very new ways of dealing with patients. Some found that very hard because they had to work hard.'

These tensions led to conflict between the former chief executive and staff members. Patient care teams in the PDU said they did not want to carry out the statutory searches on patients.

Ms Miles said: 'In an organisation like Ashworth, structure, boundaries and security are very important. Although there was room for discussion with the primary care teams, to apply the standards was mandatory.'

The inquiry is expected to continue until late spring.