‘A woman whose voice I’d never heard before was shouting, “I need to see him. He wouldn’t leave me. Vincent wouldn’t do that to me.” Or something like that. Anyway, she said she was going home. Then I heard the doctor’s voice – very deep. I couldn’t hear what he said, just a sort of growl. But she screamed at him. Something about how she didn’t need to be given anything to calm herself; she just needed to see Vincent.’

‘And you think she was Thea’s sister?’

‘I assumed so, but I didn’t care about their problems. I was so angry about the locked door that I decided to resign the next day. Thea was in a terrible state, though. She was almost hysterical and wouldn’t tell me what was the matter.’

Rosa rested her forehead on her raised knees and clasped her hands behind her neck. Hannah could see that the effort of talking was draining her already depleted energy, but after a moment, with a determined groan, she carried on.

‘I tried to calm her. She thanked me and said my voice reminded her of her sister’s. It made her feel better. Then the doctor came in with a drink. She threw it at him and asked if he was trying to kill her. When he left, I said I would make her a hot drink myself, and she said, “Thank you, Judith.” It was the first time she called me that.’

Hannah lifted her hands to wipe the tears from her face. ‘I think Judith was her sister’s name,’ she said, remembering the photograph.

Rosa stared at her. ‘Oh God, it all makes sense now. Judith left, so we each in turn became some kind of surrogate. They didn’t want her to go; they probably thought she was going to look after them into their old age.’

‘And so that became our job,’ Hannah whispered. Suddenly her whole body shook violently, and she didn’t know if this was a withdrawal symptom or was caused by revulsion at what her life had become.

‘I tried to get away,’ Rosa said, her voice distant as if she was remembering the pain of that time. ‘I told the doctor I was leaving. He begged me to stay until Thea was fully recovered. He said he couldn’t manage, but I knew she was nearly better – she was able to walk by then – so I said I was sorry. I had to go. I would leave at the end of the week.’ Rosa paused. ‘I never made it to the end of the week.’

‘What happened?’ Hannah asked.

Rosa pulled the blanket she had brought from her own room more tightly around her shoulders, and Hannah could see how much the memory distressed her.