I nod. My neck is stiff. But I’m better already for being out of the house, better already for having someone to talk to. I tamp down my thoughts, really pull it together. ‘Yes, I’m fine. I’m sorry I was so rude. I’m sorry that I made you feel awkward.’ I draw a breath. ‘Sometimes I get anxious too.’

Now Alastair’s face breaks into a smile. There is a blush too, on his cheeks. The trembling in me dies down. I glance down at Charlie, who is still gazing upwards with big round eyes. I think about all the times he’s asked me: I have a Daddy though too somewhere, don’t I? All the times I’ve wondered about Luke.

‘Listen, Jennifer, the reason I kept trying to ring you – I mean aside from checking you were okay – was because I think I’ve found another contact. An old school friend of Sarah’s. Chloe. Sarah had this old postcard from her, with her phone number on. It ended up in a book I lent Sarah, she used it as a bookmark. I spent all of yesterday looking, and I know it sounds weird, but I actually found it. I still have it – the postcard. Chloe might have changed her number since then but … maybe not.’

Now Charlie is tugging at my hand. ‘Mummy, what are you talking about?’ he says.

I shouldn’t be talking about Sarah in front of him. Not least because it’s still making my head spin. ‘It’s nothing,’ I tell him. ‘Don’t worry.’ To Alastair, I say, ‘Did you call her? This school friend – Chloe?’

Alastair colours up again, shakes his head. ‘I wasn’t sure … I thought it might be better if you did it. A strange guy calling her, out of the blue? Saying that he has her number? She might find it a bit, you know, too weird … But if you rang her? If you were able to explain?’

He pulls something from his jacket pocket, and I realize it’s the very postcard he mentioned. The cardboard is worn and crumpled, the ink all faded. It looks years old. On the front is a picture of a harbour, the word Portsmouth; on the back, the writing is almost faded away. But Alastair is right. You can make out a number.

Before I can stop myself I reach out my free hand and take hold of it.

‘And you’ll let me know, won’t you, anything you find out?’

People relying on me. Behind us, the school bell is shrilling. I nod silently, then say, ‘Yes.’

I push the card into my bag and look down at Charlie. ‘All right then, you need to go in. Time to say goodbye to Alastair.’

Charlie looks at me and I see his face fall.