‘In my defence, I wasn’t planning on it, it just happened.’ I caught hold of her arm but she shrugged it off as a cab came squeaking to a halt beside us. As the taxi pulled away, she stared silently out of the window. For the whole journey she said nothing and all I could think was that we were heading in the same direction but that she was moving further and further away.

I press the bus bell and alight. The air here feels different, conditioned and cleaned, as if in Mayfair the very air is sanitised. I walk until South Street merges into Farm Street and within a minute I am standing there at number 42B. I stare at the glossy black door. Even now, in the bright morning light, the place gives me a chill. She must be in there somewhere.

I can get the police to believe in me if I get evidence. If I find more out about him.

But now I’m here, uncertainty bleeds into me. I cross the road so that I can see the house better. The master building is a large red-brick Victorian terrace with the door to 42B tucked away beside the main run of steps. I sweep my eyes upwards and see that the sash windows above the door are shut, curtains drawn against them all. I walk a few doors along on the opposite side until I am at my earlier watch-post.

There’s nothing out of place here.

There’s still no police presence.

No police tape.

No sign of anything ever having molested the peace of this road.

Just then I see the door to the main house, 42, open, and my heart falters. This is it. A middle-aged woman appears in the doorway, steps out and turns back to lock the door. I watch as she picks her way carefully down the stone steps. Before she has managed the last step, I have crossed the street and reached her. She looks up at me as I near, her face fielding a half-smile. She is used to a world that treats her with care and kindness and she isn’t afraid of me. Because nothing in her life was ever allowed to frighten her.

‘Excuse me,’ I say. I am instinctively self-conscious but her smile reassures me as she takes me in. I am in Seb’s clothes and I am neat enough to slot into her reference so that she knows me by archetype.

‘Yes?’ she says to me, her pale eyes are those of a husky. She is older than I had thought, perhaps seventy rather than fifty.

‘I’m sorry to trouble you …’ I say. The words are forming before I have even evaluated them. I don’t know how the sentence is going to end.

‘Yes?’ I notice that she tenses her glossy cream handbag closer in to herself. I have made her anxious now.