He sighed and looked down at the file. ‘At the time, Mr Lowther appeared to be suffering hallucinations of increasing frequency and severity. Admitting himself to the unit was a very sensible decision on his part. He had good insight at that point, so he knew that he was ill.’

‘I’m not sure what you mean by insight, Doctor.’

The glasses came off, making Sinclair human again for a few moments. His eyes were pale blue. He was probably capable of projecting a reassuring bedside manner, when he thought it was necessary.

‘One puzzling feature of psychosis is that the affected individual doesn’t recognize the strange or bizarre nature of his own experiences. Even in the case of acute psychosis, a patient might be unaware that his hallucinations and delusions are in any way unrealistic.’

‘Yes, I see.’

‘However, the level of insight can vary from one case to another. There can be quite good insight in some instances. Of course, this makes the psychotic experience even more terrifying. It means, you see, that the sufferer knows exactly what’s going on. To put it bluntly, he knows he shouldn’t be seeing demons and angels, or hearing voices – but he sees and hears them nevertheless. He can’t stop himself. Try to imagine being aware that you’re not in control of your own mind any more. You’d have to accept that some of your everyday perceptions are real, but others are illusory.’

‘It’s difficult to put myself in that position.’

‘Of course it is. Believe me, when a patient is aware that he’s losing control of his own thoughts, it strikes to the very core of self-belief, and can have an extremely destructive effect on his relationship with the world around him. It undermines the concept of identity, you see. I can imagine nothing more devastating, or more terrifying.’

Sinclair put his glasses back on and peered at his visitor, assessing his reaction. Cooper was surprised by his sudden departure from the script, or rather from the notes in his file. For a few seconds, he’d spoken with real conviction. It struck Cooper that Alexander Sinclair had actually seen this happen to people he knew well – not just patients, but friends or family. Perhaps that was why he’d agreed to talk, despite the constraints of confidentiality.

‘Can you tell me what John Lowther’s auditory and visual hallucinations consisted of? Is it possible to say?’

‘In general. He heard voices that commented on his behaviour, and told him to do certain things. That’s why he admitted himself. He was frightened of what the voices might make him do, and he wanted us to stop them.’

‘And did you?’