‘Not drowning.’ I had never thought of not drowning as requiring technique. ‘Just floating, then? Floating safely?’

‘Yes.’ He waggled a finger at me, as if I was onto something. ‘Yes, floating safely. I’d treat myself to a li-lo if I could convince myself I wouldn’t drown if I fell off it. I’d just float. It’d be wonderful.’

So we worked on that instead. George lowered himself into the water with all the care of a baptism and I stood nearby as he lay on his back, water framing his face, limbs jutting like outriggers for balance.

‘It’s mostly about not panicking,’ I told him, and he said, cautiously, ‘I see, yes.’

I suggested he jump in and try to right himself, but we settled for him ducking under and trying to find his floating shape as he came up. I wasn’t sure if I was doing him any good at all as he lay there, a big old stripey English starfish, staring up at the glass roof and the sky, lips gathered into an O shape as he puffed away, water lapping at his cheeks.

After a few more attempts, he stood and said, ‘I’ll practise that. Quite exhausting, isn’t it? Perhaps I should wait until you’re here again, to supervise.’ Without pausing for a reply, he waded towards the steps. ‘Do some more of that Australian crawl, if you’d like to. Do whatever you do in pools. Enjoy yourself.’

Mrs Keene was waiting for him with a fluffy white towel when he stepped out.

I pushed off underwater and let myself glide along the bottom to the other end. I swam some freestyle, then some breaststroke, then floated on my back looking up, with my ears under, blunting the sound so that all that was left of it was distant music, strings setting up a rhythm and running with it, horns joining them in a kind of answer. Far above, a jet plane scored a white line across the pale blue sky. I watched it all the way to the roof of the neighbour’s house, wondering where it was going, who was on it. Wondering if a single one of the passengers was looking down on the red-tile and grey-slate roofs of Teddington, picking out their own house among all the others, or taking in the vast anonymous city for the last time.

When I stood up again, George was sitting at the table, his robe wrapped around him, a cup of tea beside him. The gardener was at the door, holding it open and leaning in to speak, colder outside air gusting in around him.

George interrupted him. ‘Capability, you must meet Simon.’ He indicated me with an open hand. I thought I must have misheard the gardener’s name, but then George said, ‘Simon, this is Capability, my outside man. Sorts out everything in the garden for me.’ As Capability said hello and smiled, George talked over him. ‘Simon’s from Australia. He’s one of my new neighbours. Been teaching me how to not drown. Crucial when one owns a body of water, don’t you think?’