Wim laughed. He had a strange staccato laugh, like an engine firing but failing to start. I knew without asking that scaling those walls would be easy for him, the mountaineer who has climbed the Eiger confronted by Ben Nevis. All in the day’s work, no more arduous than going up a ladder. He squatted on the coping, placed his hands on the stone to the right of him without recourse to pipes or ivy, and sprang down, light as a dancer. Anyone in the rooms beneath would have heard a soft thud and thought nothing heavier than a squirrel had landed on the tiles. He ran across the roof, which was almost flat. The night wasn’t dark. Inner London is never quite dark. But when he reached the other side his figure had become indistinct. It was a silhouette we saw climb the gable end, but “climb” is not the word for what Wim did. We were climbers, Silver a very good one. Wim walked up walls, danced up them, ran up them, negligently waltzed across gambrels and sprang without fear or even thought across pitched roofs.

He vanished from our sight. Silver laughed, said to me, “One day I’ll tell you some of the things he has done.” He took my hand and Liv’s. Her face was all woe because Wim had gone. “Now what we’ll do is drop down there. Liv’s done it before. The coping gives you a good handhold.”

I went first, holding the smooth cold surface of the pipe, choosing footholds in the ivy forks to drop, noiselessly as I hoped, onto the roof. It was a slab construction, with a television aerial, a big insulated tank of some kind, and a chimney containing three flues. I walked as lightly as I could but failed to rival Wim. Liv came next, hesitating a bit like an apprehensive swimmer on a diving board, then Silver. We climbed the gable end, finding the nailhead projections, little shallow pyramids, helpful as hand- and footholds, the next best thing to steps. It was a wide gable, the roof of Torrington Gardens was low-pitched, though steeper than that of Russia Road, and made of similar gray slates. How many slate quarries were there in the world, I wondered. Were there any left or had we plundered them all to cover and insulate and protect in warmth and comfort Maida Vale?