But two centuries in London was nothing more than a slow blink, and you didn’t need an antique map of London to find Three Cranes Wharf. It was right there—as Three Cranes Walk—on page 94 of my London A to Z, alongside Southwark Bridge.

The next afternoon the Centenary of Federation was able to manage without one of its writers: I had a couple of hours to myself. Guidebook in one hand, umbrella in the other, I made my way towards Three Cranes Walk.

Down there in the East End, by the river, was where some of the worst of the bombing took place during World War II. Now it was all big blocky office buildings in undistinguished 50s and 60s architecture. Street names, like archaeological remains, were the only evidence of what had once been here: Bread Street, Milk Street, Pudding Lane.

Until the last hundred years you’d probably have been able to see the river from all these streets, glinting between the low tight-packed buildings and the grey stone churches. All that remained now was the fall of the land, the streets flowing down the hill like streams.

I followed the slope but at the last moment, just when I thought I’d get to the river, I was blocked by a multi-lane road buried between office buildings. The din of trucks, motorbikes, cars at speed, was unremitting. I was conscious of how frail my body was compared to the lorries, the blank-eyed cars and the deafening bikes hurtling along this tube of bitumen.

No one ever waited for the traffic lights to let them cross as long as I did at Lower Thames Street, E3. By the time I got to the other side I felt shellshocked.

There still seemed no way to reach the river. A solid wall of buildings lined the road. If not for the map, fluttering in my hand in the slipstream from the lorries, I wouldn’t have guessed the river was there, a building’s thickness away.

With some sense of finding a sanctuary, I turned towards a church. It was like so many others: grey limestone, streaked and smeared with poisoned rain, some columns holding up a portico.

Down a narrow alley beside the church, a man in a stained polo shirt, an airline bag across his chest, was crouching to pick up a scattered mass of cigarette butts. He dropped them into his bag and scurried on, head down, scanning the footpath and the gutter.

Apart from the polo shirt and the plastic airline bag, he might have stepped out of Wiseman’s London. Wiseman himself might have walked here, stood under this portico to shelter from the rain. I laid the palm of my hand on the rough limestone, feeling the cold grit on my skin. His hand might have lain there too, leaving molecules behind, wedged in the grain of the stone, as he leaned on it talking to someone, or waiting for someone, or…what? Smoked a pipe? Drank from a flask in his pocket? Scratched the nits in his hair?