‘Fine,’ I said. ‘I’m used to looking after myself, anyway.’

Oh well, Dad would probably have cleared off for a swim too, if he’d wanted.

Mark slipped off his espadrilles and I took in the sight of his bare feet with scientific interest. I wasn’t really used to seeing men’s feet. Mum’s feet were wide and pale and soft, almost child-like. Ava’s were annoyingly elegant and she was proud of them, though she wouldn’t admit it. She spent ages painting her toenails, and she was always going around in little strappy sandals, as soon as the weather warmed up enough. But bare male feet were a rarity in my life.

Mark’s were probably quite attractive, not that I had anything to compare them to. He had very high arches and very large big toes, and a sprinkling of freckles and no obvious sprouts of hair – a good thing, in my opinion.

Would Mum object to finding his toenail clippings in the bath? No – because Mark would never, ever leave them there. He’d always check, and rinse the bath as much as was necessary to remove every last trace of himself. In fact, he was probably the kind of person who would clean the bath before he used it.

Mark unbuttoned his shirt and took it off. His back was smooth and unblemished – no hair, no scars, no moles, no identifying marks. I tried to remember if I’d ever seen Dad with no top on. I didn’t think I had.

Suddenly Dad seemed a very, very long way away, which he was, as far away as someone can be. I had no idea where he was. He could have been anywhere. And you can’t get further away than that.

I tried to summon Dad up: perhaps I could get a picture of where he was, at least, or a flash of how he was feeling.

Nothing. The knowledge didn’t seem to work like that, or do anything I might actually want it to do. Sometimes I wondered what on earth was the point of it, what it was for. It certainly didn’t seem to be there to help me.

Mark stood up and unzipped his trousers and stepped out of them. He had his swimming trunks on underneath. I quickly looked away, over towards the expanse of the sea. It really wouldn’t do to stare, especially if he noticed.

Presumably, when he was married to Mum and we were all living together, he’d go round in a dressing-gown at home like we all did? It would be less awkward and strange when we were all used to each other, anyway. Wouldn’t it?

‘Back in a bit,’ he said, and went off across the sand to the sea.

Poor old Dad. He’d let Mark hit him… he’d slunk away as if he wasn’t even entitled to be there.

I watched Mark launch himself into a fast front crawl and churn his way through the water. As I looked on the waves seemed to become stronger and greyer and darker, as if a storm had blown in from somewhere, as if this wasn’t such an idyllic spot after all.