Former judge Peter Fallon QC is to head the investigation - which starts tomorrow - into the hospital's Personality Disorder Unit, where it is alleged inmates abused an eight-year-old girl who was prostituted by her own father, a former patient. The inquiry will examine other allegations that inmates used computers to access child porn Internet sites and that there was widespread drug-taking.
Brian Katon, POA assistant secretary, said: "These people generally need control. They have committed some horrific offences. When patients of a violent nature who are severely disturbed wander around with low levels of staff, they are a danger to themselves, to other patients and to staff."
A spokeswoman for the hospital would not be drawn. "The POA is entitled to its opinion, but the opinion that we're interested in is that of Sir Peter Fallon," she said.
If the inquiry report recommends a tightening of security, it would reverse a more liberal policy introduced in 1992 after another inquiry, led by Sir Louis Blom-Cooper QC. Disturbed patients were offered aromatherapy, computers and allowed to elect advisory ward councils. They were also given the right to roam the hospital grounds, which is where many of the attacks on the girl were alleged to have taken place.