Susan walked in and sat on the sofa. ‘The kitchen’s been done up,’ she said. ‘But she always had this room nice. I never saw inside the bedroom. She always had the door shut.’

‘Did she enjoy it?’ He repeated the question. Thinking about it again, it wasn’t so much the sex that shocked him, but the fact that it had happened here, in Margaret’s own space. It seemed like a terrible invasion of her privacy, another example of living on the job. He could see why she’d invited so few people into her home once she’d retired.

‘She said it was better than working for a living. And once she’d got herself sorted, her own clients – regulars – I think she did like it. She only ever took on someone new if they were recommended. She never had to advertise.’

‘Not like Dee Robson?’

Susan gave a sad chuckle. ‘Poor Dee. She was an alcoholic and she enjoyed the drink too much to give up. Every couple of quid was important. And she needed the attention. But she was never a real professional. Not like Margaret.’

Joe sat beside her. ‘Did Margaret ever talk to you about her customers?’

‘Clients,’ Susan said. ‘She called them her clients. And no, she never talked about them. She said she was like a doctor or a priest, and what happened in the bedroom stayed secret.’

Joe took another tack. ‘Where was your room?’

‘On the ground floor. Near the front door. Draughty. And I never got it looking like this place.’ She looked wistfully at Margaret’s furniture. ‘Didn’t have the eye.’

‘But you’d have seen people coming in and out from there?’ Because Joe thought Susan would have been curious. Jealous even. He pictured her peering through stained net curtains, catching a glimpse of Margaret’s gentleman callers on the pavement outside.

‘Sometimes.’ Susan snapped her mouth shut, as if she’d just remembered that this pleasant young man was a police officer.

‘It might help us to find out who killed her,’ Joe said. ‘We think it might have started all those years ago.’

‘Nah! That’s just daft. Who’d care what happened then?’

‘Margaret was dying,’ Joe said. ‘Bowel cancer. We think she wanted to talk about what happened back then. And maybe somebody wanted to stop her.’

There was a pause. On the roof outside herring gulls were screaming. ‘I never knew their names. And there were only a few of them.’

‘But you saw them.’

‘All respectable,’ she said. ‘Suits, you know. Shiny shoes.’ She leaned forward and lowered her voice. ‘Once there was even a vicar. He was wearing a scarf, but when he was leaving it was open at the neck and I saw that white collar they have.’