‘It’s a possibility, surely? We don’t know what happened. Maybe we never will. All of us feel guilty to some extent. I failed her. I have to live with that.’

‘I’m sorry.’

‘It doesn’t matter,’ she says brusquely. ‘We all failed her one way or another.’

What do I really feel about this woman? I’ve only known her a short time, and yet here we are, part of each other’s emotional experience, her head full of what happened eighteen years ago, mine full of what’s happening now. We’ve both experienced loss, but she’s accustomed to hers, while I wear mine like someone else’s clothes.

She takes me into an attic room furnished with twin beds. She sits down on the end of one of them, and I sit on the other. The room is long and narrow and has skylights either side of a pitched roof and a small window at each end. The windowsills are scattered with the carcasses of long-dead insects; flies on their backs with their tiny legs in the air. Sun-shredded curtains hang from yellowed curtain wire. There’s a camp bed folded up against the wall. It smells strange, not just of dust and damp, but of human occupation. Maybe the twins still use it. Or their kids, if they have them. Whatever, the place needs airing.

Anna sees me wrinkle my nose. ‘It’s not exactly five-star luxury, but Pansy, Freya and I always had this room; it’s the furthest away from the adults.’

‘Did Nick ever come up here?’

She looks down at her hands. ‘No. He was banned. I’ll show you his room. Come on.’

The room where Nick slept was on the first floor, down a corridor and round into the north wing. It’s large and chilly, but a lot cleaner and better cared for than the attic room and it doesn’t have that musty smell. Anna stands in the doorway while I look around. I inspect the bookshelf, wondering if Nick found solace in books that summer. They are a mixture: crime and young adult, classic and chick lit. Coincidentally, one of them is the thriller Nick was reading when he left. It’s still beside our bed in London. I pick it up and run my thumb over the cover. It’s dusty.

‘Their friends leave books behind when they come to stay,’ Anna says. ‘That’s nice, don’t you think?’