The interior of the building looked like the inside of any nursery or playgroup. A couple of small slides and a miniature climbing frame in the shape of a train in the centre, toy cupboards all around the edges, posters of Teletubbies and Peppa Pig stuck up around the walls. To the right was a counter where, Patrick imagined, the staff served cups of coffee to exhausted parents and orange segments and triangles of toast to energy-burning pre-schoolers.

Jemima pulled up some plastic chairs and sat down on one, gesturing for Patrick and Carmella to do the same.

‘You’re the manager here, is that right?’ Patrick asked.

‘Uh-huh.’ The woman’s legs bounced with nervous energy. She made Patrick feel like grabbing her knees and forcing her to stay still. ‘I can’t believe it. Those poor babies. Little Isabel. You know, I thought I recognized her. I said to my husband, I know that pretty little face. But we get so many children here.’

‘Mrs Walters, you do understand this conversation is confidential? We need your discretion. It could be vital.’

Her eyes met his, a little flash of excitement to go along with her distress. She was important. Trusted.

‘You have my word,’ she said.

‘Good. Can you tell me a little about this place first?’

She explained that the Eleven O’Clock Club was a centre run by the council, her employer, to provide a place for parents to take babies and pre-school children every weekday morning. ‘It’s hugely popular. Sometimes I think we’re the very heart of Nappy Valley.’

‘And on Saturdays you run the Dads’ Club?’

‘Mmm. Although that’s not its official title, you know. That’s just what everyone calls it. Mums and grans and granddads are welcome too. Anyone. But we get a lot of fathers on Saturday morning, giving their wives a break from the little ones.’

‘I’ll have to check it out,’ Patrick smiled. ‘I’ve got a daughter who’s just about to turn two.’

‘Oh, please do.’

‘Do you keep records of everyone who attends on Saturdays?’ Carmella asked.

Jemima stood up, went behind the counter and fished out a book from a drawer. ‘This is the signing-in book. To be honest with you, we don’t enforce it, but everyone who comes in has to sign in and out, and give their name, the names and ages of their kids, their postcode and phone number. Plus there’s a voluntary two-pound fee that goes towards snacks and drinks.’

‘Can we borrow this?’ Patrick asked.

‘I . . . don’t know.’

‘We’ll look after it.’

‘Why do you need it? Why are you here?’ Her knees were jiggling faster than ever now.