‘Can you manage this?’ I asked as we reached the matron’s house. It was closer than mine and there weren’t as many stairs. Warren hesitated for a moment, then lifted one foot and planted it on the bottom step. ‘That’s the way,’ I said. ‘Just two more. Hups-a-daisy.’

We got to the top, but it nearly killed Warren. He was reeling when we arrived on the veranda; I had to prop him against a post while I unlocked the front door. The beds inside were all made up, except for the one I’d taken the mattress from. There weren’t any towels, but everything was squeaky clean. The whole place smelled a bit stale.

I managed to haul Warren into the second bedroom, where he dropped onto the bed like a felled tree. He lay there, groaning, while I wondered what to do next. Raid my bathroom medicine cabinet?

‘Hang on.’ I leaned close, squeezing his shoulder. It was sodden. ‘Have you got some spare clothes in your hut?’

He muttered something about his rucksack.

‘Okay. I’ll look.’ I began to unlace his boots, but it was difficult; the knots had fused into tight little wet balls. At last I managed to unpick them and yank his boots off. ‘I’m just ducking out, okay? Don’t move.’

I locked him in when I left the house; it felt safer. Then I crossed to the other side of the compound, where the huts stood in neat ranks like soldiers on parade. Warren had been assigned hut number three. I found his rucksack sitting on the polished floor beside a flawlessly made single bed. It didn’t feel right, digging through his possessions, though they were mostly clothes and toiletries. I was surprised to find a biography of Charles Dickens. I would have expected a war-hero memoir.

Warren had packed spare underpants and socks, but all his other clothes were ready for the wash. They had a distinctly Warren-ish smell—a mixture of sweat, deodorant and slightly flowery soap. I picked out a white T-shirt and a pair of trousers and tucked them under my arm. On my way back to my own quarters, I tried to remember what I’d learnt about head wounds in my most recent first-aid course. Rule number one was that you shouldn’t move the patient. But how could I have left Warren in the path of an incoming tide?