‘Then I haven’t described it properly. The fact is, not everyone finds psychosis a negative experience. While some patients suffer persecutory or self-blaming delusions, others develop grandiose fantasies or have an experience of deep religious significance. This can appear very positive and life-affirming.’

‘Are you serious?’

‘Absolutely. I’ve known some individuals describe a psychotic episode as a revelation, a wonderful and exciting new way of seeing the world – in fact, the sort of experience that people seek from hallucinogenic drugs. You know, a surprisingly large percentage of the population have undergone a psychotic episode of some kind, without being disturbed by the experience. At the end of the day, a hallucination is merely the misattribution of internal events to an external source.’

Cooper shook his head, trying to throw off a sudden, unwelcome burst of insight, a glimpse of how it might feel if the reality of his own world became suspect. He was sure he would find it disturbing.

‘Could we get back to the question of John Lowther’s condition, and how he was being treated?’

‘Well, when Mr Lowther was discharged, he returned to the community. He has family members in Derbyshire. It’s normal practice to ensure that the family are fully aware of the importance of maintaining medication. We can’t be there standing over every patient personally, to make sure they take their drugs.’

‘Who was supposed to do that? His parents?’

Dr Sinclair frowned at the file. ‘According to his records, there’s a sister.’

‘She’s dead.’

‘Oh.’

‘And I think she might have been too preoccupied recently to worry about her brother.’

‘Mr Lowther must have been due for a review,’ said Sinclair. ‘Perhaps his GP had examined him recently.’

They looked at each other for a moment, conscious of the futility of trying to work out where and when the system had gone wrong.

‘Basically, a dangerous psychotic was allowed out into society unsupervised,’ said Cooper.

‘No, no, you don’t understand. Once a patient is discharged and living at home, clinicians are helpless. Even if we know they might be a risk to themselves and others, we can’t force an individual to continue medication. Not at present.’

‘But you’d like to be able to compel people to take their drugs?’

‘Detective Constable, fifty thousand patients are detained by psychiatrists every year. If we can’t compel people to continue medication when they’re back in the community, all that happens is that some of them get very ill again and have to be detained a second time, or a third. It just goes on and on.’

‘The revolving door approach. We see it often enough in the courts.’