‘Sometimes a girl came to us from a family that was functioning, to a certain extent anyway, but which had reached a crisis and needed short-term help, or maybe long-term, but either way the building blocks, though flimsy, had been stable. For the most part,’ she added. ‘Those girls were easier to help because they had things we could work with, an understanding of social norms, of consequences. But some girls came to us with none of this. They had no blocks on which to build a life. They were, to risk using a tabloid trope, feral.’

‘Which types were these two girls?’

‘Well, Aoife was a girl who’d had no foundations whatsoever. Her family – and I use that in the loosest sense of the word – had been chaotic and in crisis more often than not. She’d been in and out of care since she was one, but she also had a sensitivity which hadn’t been beaten out of her, despite all attempts. In contrast, the other child was one we thought would only be with us for a few weeks, but as the months went on and her mum didn’t want to have anything to do with her, we lost her. I don’t think she could ever get over her mum choosing her dad over her, and she kept expecting her to turn up any day, which of course she never did.’

‘Aoife was the murdered child, yes?’

Harriet nodded. ‘Yes. So very tragic. Aoife was one of those girls who pretends they don’t care about anything because that way no one can hurt them. But with Mary she was different, maternal even, so it was especially lovely to watch the two of them form such a bond.’ She gave a short laugh and settled back in her seat, teacup in hand.

‘Mary?’ Nell looked at Carla, who was clearly as stunned as she was.

‘The second child on the beach was called Mary?’

‘I will never forget those two children as long as I live. So yes, I’m quite certain she was called Mary. Mary Balcombe.’ She smiled. ‘From the moment the girls met they were inseparable. We used to joke in the office. “Who’s seen the duo today?” we’d ask, and one of us would always have seen them – on the beach, at McDonald’s, in town.’ She looked down at the floor and shook her head.

‘What happened to Mary, after Aoife died?’

‘Well, naturally we all thought she’d fall apart. But she seemed to gain some inner strength and after the initial grief, she pulled through quite well, all things considered. Worked hard at school – turned out she was as bright as a button when she put her mind to it – and scored almost the highest in her year in her end of school exams.’

‘Was Mary ever implicated in the death of Aoife?’