‘Where she was living when she died.’ He opened his eyes again. ‘That flat in Harbour Street. The house was very different then, but her rooms were always clean, pleasant. You’d walk up the stairs past the sound of kids grizzling and the smells of cooking, and then you’d go into her place. Everything calm and warm. Like going into a different world. I went for that, as much as for the sex. The escape from reality.’

‘She worked from her home?’ Joe was surprised by that. All the working girls he knew were fiercely protective of their privacy.

‘I think she’d looked into the possibility of finding a place to operate from, but she said she’d been ripped off. She’d rather trust her clients than the sharks who preyed off sex workers. And there weren’t many clients. We paid well. She was worth it.’

Joe was suddenly intensely curious about what had gone on between these two people. Despite himself, he imagined them in the attic room in Harbour Street, the shy young teacher and the slightly older woman, who was taking money for sex. He found himself wanting details. Perhaps Booth guessed what he was thinking because obliquely he answered the unspoken question.

‘Anna was amazing.’ He paused. ‘I counted the days until I could see her again. Though, looking back, I suppose it wouldn’t have taken much to please me. I was young and awkward and she was older and more experienced. Kind. And there was the thrill of the illicit. I never told anyone about the encounters, not even the friend who’d passed on her name. I loved the fact that our meetings were secret, that the next day I would walk into school to be a respectable, responsible teacher and nobody had any idea what I’d been doing the night before.’

‘Why did it stop?’ Joe asked. ‘I take it that it did stop?’ He couldn’t imagine this man in his late fifties climbing the stairs to see Margaret when Kate wasn’t looking.

‘I found a girlfriend, Sergeant. Not someone I cared for as I do about Kate, but someone to sleep with. That was less exciting than the visits to Harbour Street, but it seemed more appropriate. And as I got older I lost my courage. I was scared someone would see me. I couldn’t have stood it getting out that I used the services of a prostitute.’

‘Did you ever meet any of Margaret’s other clients?’ The thought came to Joe quickly. A sudden flash of hope.

Booth shook his head. ‘No. As I say, I think we were a select bunch. Margaret presented a respectable face to the world too. A couple of times I saw the back of a man disappearing down Harbour Street in the gloom as I came in. But no faces. Nothing that would be of any use to you.’