We know this too, but no one interrupts.

‘But after Dad …’ Kate swallows, and I know the bad part is coming, the time none of us can bear to think about. ‘After Dad … disappeared, Luc – he couldn’t stay here any more. He was only fifteen, I turned sixteen that summer, but Luc was still several months off and a minor, and in any case once social services got involved …’ She swallows again, and I can see the emotions passing across her face, cloud shadows flitting across a valley.

‘He got sent back,’ she says abruptly. ‘He wanted to stay here with me, but I had no choice.’ She spreads her hands out pleadingly. ‘You realise that, right? I was sixteen, there was no way they were going to let me act as legal guardian to a stray French boy with no parents in the country. I did what I had to do!’ she repeats, her voice desperate.

‘Kate.’ Fatima puts a hand on her arm, her voice gentle. ‘This is us, you don’t have to justify yourself. Of course you had no choice. Ambrose wasn’t Luc’s dad – what could you have done?’

‘They sent him back,’ Kate says, almost as if she hasn’t heard. Her face is blank, remembering. ‘And he wrote and wrote, pleading with me, saying that Dad had promised he’d take care of him, and accusing me of betraying him, accusing me –’

Her eyes well up with tears, and she blinks them away, her expression suddenly bleak and raw. Shadow, sensing her unhappiness without understanding it, comes to lie at her feet, with a little whine, and Kate puts her hand down, ruffling his white fur.

‘A few years ago he came back, got a job at Salten House as a gardener. I thought all the years would have given him perspective, that he’d have realised that I had no choice. I could barely keep myself out of a children’s home, let alone him. But he hadn’t. He hadn’t forgiven me at all. He cornered me one night coming back along the river, and oh God –’ she buries her face in her hands – ‘Fatima, the stories! You must hear them all the time as a GP, but I’d never – the beatings, the abuse, God, what he –’ her voice cracks – ‘what he suffered – I couldn’t bear to listen, but he kept on and on, telling me, like he wanted to punish me – what his mother’s boyfriends had done to him when he was little, and later when he went back to France and got taken into care, the man at the children’s home who used to – who used to –’

But she can’t finish. Her voice dissolves into tears, and she covers her face.

I look at Fatima’s and Thea’s shocked faces, and then back to Kate. I want to say something. I want to comfort her, but all I can think is how they used to be, the two of them, their laughing faces as they splashed in the Reach, their companionable silence as they bent their heads over a board game … They were so close – closer than my brother and I ever were. And now this.

In the end it’s Fatima who sets down the plate of food very carefully, and stands. She puts her arms around Kate, rocking her, wordlessly, back and forth, back and forth.

She’s saying something, very low, but I think I can make out the words.

‘It wasn’t your fault,’ she’s saying, over and over. ‘It wasn’t your fault.’

I SHOULD HAVE known. That’s what I think, as I sit by Freya’s crib, trying to lull her into sleep, with a pain in my throat from unshed tears.

I should have known.

Because it was all there in front of me, for me to see. The scars on Luc’s back as he swam in the Reach, the marks on his shoulder that I assumed were botched inoculation scars, but when I asked him about them, his face only twisted and he shook his head.

I am older now, less innocent. I understand those small circular burns for what they really were, and I feel sick at my own blindness.

It explains so much that I never understood – Luc’s silence, and his dog-like adoration of Ambrose. His unwillingness to talk about France, however much we pestered him, and the way Kate would squeeze his hand, and change the subject for him.

It even explained something that I had never understood – the way he would let the village boys tease and mock and swagger at him, and he would just take it and take it and take it … and then crack. I remember one evening in the pub, when the village kids had been ribbing him, gently but relentlessly about hanging out with ‘snooty’ Salten House girls. Luc’s position, not quite town, not quite gown, had always been a tough one. Kate was firmly Salten House, and Ambrose somehow effortlessly straddled the two worlds. But Luc had to negotiate an uneasy class divide between the state school in Hampton’s Lee that he attended with the majority of the village kids, and his family connection to the private school on the hill.

And yet, he managed. He put up with the teasing, the ‘our girls not good enough for you, mate?’ remarks, and the veiled comments about posh girls liking a ‘bit of rough’. That night, in the pub, he had just smiled and shaken his head. But then, right at the end of the night, as last orders were being rung, one of the village boys bent down and whispered something in Luc’s ear in passing.

I don’t know what he said. I only saw Kate’s face change. But Luc stood, so fast his chair hit the floor behind him, and he punched the kid, hard and straight on the nose, as if something inside him had snapped. The boy fell to the ground, gasping and groaning. And Luc stood over him as he bled, and watched him cry, his face as expressionless as if nothing had happened at all.

Someone from the pub must have called Ambrose. He was sitting in the rocking chair, waiting for us when we got in, his normally good-humoured face without a trace of a smile. He stood up when we entered.

‘Dad,’ Kate said, breaking in before Luc could speak, ‘it wasn’t Luc’s –’

But Ambrose was shaking his head before she’d even finished.

‘Kate, this is between me and Luc. Luc, can I speak to you in your room, please?’

They closed the door to Luc’s room, so we couldn’t hear the ensuing argument, only the rise and fall of the voices, Ambrose’s full of disappointment and reproach, Luc’s pleading, and then at last angry. The rest of us huddled below in the living room, in front of a fire that we barely needed, for the night was warm, but Kate was shivering as the voices above us grew louder.

‘You don’t understand!’ I heard from above. It was Luc’s voice, cracked with furious disbelief. I could not hear the words of Ambrose’s reply, only his tone, even and patient, and then the crash as Luc threw something at the wall.

When Ambrose came down, he was alone, his wiry hair standing up on end as if he’d raked it through and through. His face was weary, and he reached for the unlabelled wine bottle under the sink and poured himself a tumblerful, downing it with a sigh.

Kate stood as Ambrose sank into the armchair opposite, but Ambrose shook his head, knowing where she was heading.

‘I wouldn’t. He’s very upset.’

‘I’m going up,’ Kate said defiantly. She stood, but as she passed Ambrose’s chair he put out his free hand, catching her wrist, and she stopped, looking down at him, her expression mutinous. ‘Well? What?’

I waited, my heart in my throat, for Ambrose to explode as my father would have done. I could hear him now, raging at Will for answering him back, I’d have been thrashed for cheeking my father like that, you little shit, and When I give you an order, you listen, got it?

But Ambrose … Ambrose didn’t shout. He didn’t even speak. He held Kate’s wrist, but so gently, his fingers barely circling it, that I could see that was not what was keeping her there.

Kate looked down at her father, searching his face. Neither of them moved, but her expression changed, as if reading something in his eyes that none of the rest of us could understand, and then she sighed, and let her hand drop.

‘OK,’ she said. And I knew that whatever Ambrose had wanted to say, Kate had understood, without needing to be told.

There was another crash from above, breaking the silence, and we all jumped.

‘He’s trashing his room,’ Kate said under her breath, but she made no further move towards the stairs, she only sank back down to the sofa. ‘Oh, Dad, I can’t bear it.’