I set down my glass. ‘Bill . . . you were in the garden last night. Did you see anything? Did anyone come in the gate?’

He shook his head slowly. ‘I went to bed before . . . anything. But the police checked the tape from next door, didn’t they?’ Anna had already told me as much. Nothing had shown up.

‘But . . . did you see anything else? From the upstairs windows, maybe?’

He paused. ‘I looked out the landing window when I went to the loo. I guess it was . . . not long before it happened. I’d got back into bed and was half-asleep when . . . the shouting.’ I understood. The landing window overlooked the garden.

‘You’re saying, what, you saw them in the garden? Last night?’ My hands started to shake; I set the glass down. No, it couldn’t be. I wanted to shout, please don’t say it.

His face was screwed up. Bill hated this, other people’s messy lives. ‘I didn’t know for sure, not at the time. But I think I . . . I saw him on top of her, Ali. It was dark, but I could see his clothes. But I thought . . . well, obviously I didn’t think it wasn’t consensual, or I’d have rushed out there. I keep thinking about it. I saw it happen and I just left her there.’

‘You thought they were . . . together?’ Having sex, right there in the middle of our lawn. It seemed unbelievable. I thought of myself, asleep in bed, oblivious, and I wanted to shake the clueless woman that I’d been just the day before.

He looked uncomfortable. ‘I – they seemed quite flirty earlier on. I didn’t want to interfere in whatever was going on. I’ve not seen you all in years, I couldn’t just rock up and start – you know.’

Same thing Jodi had said. Did everyone know except me? I couldn’t think about Karen, couldn’t let myself feel sorry for her. It was horrible, as if she was clinging to a rope, begging for help, and I was sawing through it. ‘You definitely saw him?’

‘I think so.’

‘Did you tell the police?’

He nodded. ‘I’m sorry. I had to.’

‘Mike told me they had sex earlier that day. While I was out.’

Bill looked like he’d rather be undergoing dental extraction than having this conversation. ‘Maybe they did that too.’

The proof was there. Bill had seen them, and the semen was there, and no one else could have got into the garden. All that remained was Karen’s word it had been against her will.