‘We had guests. Friends, family, neighbours. It was a private affair. Right at the end of the service, as we were walking out, I noticed a woman sitting at the back of the church. She was . . . different somehow.’

‘What do you mean?’

‘I can’t properly explain. It was the way she was looking and not looking.’

‘I don’t understand.’

‘Neither do I, really. I mentioned it to your dad, but you know what he’s like. He thought I was being whimsical.’

‘What was she like?’

‘It was a bit of a blur. I remember she wore a coat and hat. I guess it covered her up. Maybe that’s what I meant about looking and not looking. She was obviously there for a reason, and perhaps she’d just got the wrong time or place – but it seemed as though she didn’t want to be seen, or something. But I didn’t really think anything of it at the time. I was preoccupied with you, and making sure I thanked people for coming.’

‘Right,’ says Marina slowly. ‘And nothing else happened?’

‘Well.’ Ruth pauses. ‘The thing is, I thought I saw her again. Or should I say something similar happened. It was twenty years later, so I couldn’t be sure it was the same woman.’

Marina feels a sliding sensation. ‘When was it exactly?’

‘At your graduation ceremony.’ Ruth gives a short laugh. ‘I know what you’re thinking. It’s stupid, isn’t it?’

Marina rubs her forehead. ‘Did you speak to her?’

‘No. It was a crowded room. By the time I decided to approach her, she’d gone.’

Marina closes her eyes. Why hadn’t Ruth told her this before? ‘Did you talk about it to Dad that time?’

‘No. It was silly. Honestly, Marina, I decided it was a coincidence and that it couldn’t possibly have been the same woman. I put it out of my head. At least I tried to. Your saying what you said about Sofía . . . Well, I suppose it brought it back.’

A week passes. Marina stops exploring London and focuses on the house. She paces the dusty hall gauging its length and width as if long forgotten secrets will be revealed through mathematics. She examines the alcove on her hands and knees, considering the angle of the door, calculating how many seconds it would have taken to come in and leave the baby. It would have been risky, she thinks. Either of the tenants in Flat 2, Eileen or Leonard, could have come out and discovered her – or the landlord for that matter, Kenneth Quip. She peers at the post boxes as if they might hold the key to the past. None of them have locks. The box belonging to Giovanni Gaetti in Flat 1 is so full the flap hangs open.