‘It’s a delusional disorder in which the sufferer mistakenly believes that a person present in their environment is a familiar person in disguise. Leah might see his face, or she might get a sense that it is him masquerading as someone else. It is very real to her. She believes wholeheartedly that he is persecuting her.’

‘I’ve never heard of this.’

‘As I said, it’s rare but we believe if more health professionals were aware of it then the number of diagnoses would increase. I believe a proportion of cases where people report they are being stalked could be because they have Fregoli.’

‘And you can just… catch it?’ He steps backwards as though I am contagious.

‘There are several known causes. Leah hasn’t sustained a head injury but she suffers with other mental health issues, which can cause an onset of Fregoli. For instance, Leah has contamination OCD, paranoia and panic disorder. Every incident where Leah claims she is being followed is very real and very frightening to her. She thinks she sees his face everywhere, or sees him disguised as other people, but it’s not him.’

‘Right…’ You could see the officer was having a hard time believing her. ‘If Leah is sectioned she can be treated and—’

‘I believe sectioning Leah will be counter-productive. She’ll still see his face or think he is disguised as a nurse—’

‘She might think he’s a woman?’

‘It’s possible, yes. She’ll think he’s clever enough to carry that off. If she’s sectioned she will have the added trauma of being in a locked ward with no familiar faces and no way to escape. She needs medication and therapy, but not to the extent of drugging her to an almost vegetative state. She needs to feel safe.’

‘I don’t know. It all sounds fuc— so unbelievable. No offence.’ He looked at me and then turned quickly away as though I might cause his face to change. ‘And this is one of them newfangled mental health thingies we’re supposed to be sensitive about?’

‘It’s not new.’ Francesca didn’t show any hint of impatience. ‘The first diagnosed case was in 1927. A theatregoer was convinced that two of her favourite actresses were disguising themselves as other people and following her. Her theory was… disproved,’ Francesca said carefully, not adding that the theory was disproved after the lady attacked a stranger, thinking it was one of the actresses, as I found out later. ‘The condition was named after Leopoldo Fregoli, who thrilled Victorian theatregoers with his quick-change act. Look. You can discharge Leah into my care. I’m confident I can treat her. Once the anniversary is over, the pressure will be off anyway and it will likely disappear as quickly as it came on. You do all know what she went through as a child.’

‘Yeah.’ This time his voice was softer, he probably had children of his own. ‘Okay. You can take her home. But she better not be back in five minutes reporting she’s seen him again.’