“Before we get on to ‘time’s winged chariot,’ ” said Silver, and I think he said it to distract Wim from some threat or dread, “I’m going to tell Morna not to come. Not this time. We don’t take risks, remember? Come on, Morna, there’s a dear, home time. I’ll see you out.”

It was his custom to escort visitors out, especially women. I doubt if I ever left there without his accompanying me to the front door and down the path. But then, of course, I was different. He came back, running up the stairs two at a time, we could hear him, light on his feet as he was. It was twilight then and the sky was the dusky red of Wim’s tunic. One by one we climbed out of the window onto the roof.

Liv and I were empty-handed but Wim and Silver each carried a coiled rope and Wim hooks as well, and Jonny had his backpack. Later on I learned that Jonny took no pleasure from the roofs but saw climbing on them only as a means to an end. Climbing out of the casement was easy, the only tricky bit being hauling oneself up into the ellipse of the dormer, and after that it was a matter only of scrambling up a few feet. Silver did it with practiced expertise, Wim with a wonderful elegance.

We crossed the roof to the front and squatted on the flat shelf of the mansard, on its smooth gray slates, and looked at what we could see, Russia Road, car-lined but empty of moving traffic and empty of people, still, silent, and deserted. The streetlights were on but their lit lamps were far below us. Above was half-dark, the nighttime twilight of London, and beneath all was shiny, golden, and crisscrossed with leaf shadows that trembled in the breeze. The roof where we were was a shallow slope, almost flat. We walked across it, Silver taking my hand. I was afraid of dislodging slates but I quickly learned the technique of avoiding this. Roof walking demands lightness and precision, it’s not for your stolid plodder. We sat down and surveyed the panorama from the back, where there was no immediate, correspondingly high, rampart of houses to impede the view.