I wrote a whole story about him as I glanced at that sad finger. ‘Here, son,’ the father said as he gave him the shiny new briefcase, too embarrassed to kiss or embrace or even shake hands, only giving a hard slap on the boy’s puny shoulders. ‘Now you’ve started at work.’ The father dying, of course, but the son hanging onto the relic, having it stitched crudely at the shoe-repair place when it started to go on the corners, the memory of his father embedded in the worn old thing.

Now he was a seedy balding middle-aged man trying to pick up a frowning tourist in Lower Thames Street, and wondering what he’d got himself into. ‘Why do you want to find it?’ he asked.

‘Just a bit of family history,’ I said, a fraction shamefaced now, half-regretting my rudeness. ‘A family connection.’ I didn’t want to launch into the whole story about Wiseman in case I couldn’t get rid of him.

‘Look, it’s down here,’ he said again, and turned away without waiting to see if I was following. At a rapid speed he led me into what seemed like the inside of one of the faceless office blocks, into a kind of tunnel underneath. We turned a corner and the traffic noise was cut off. I could hear our two sets of footsteps fast on the pavement. He led and I followed a few yards behind.

This was stupid. If I disappeared off the face of the earth here, there’d be no one to guess where I’d gone.

But I kept following, at a distance. He led me across a laneway, down some stairs, along an alley between two towering office blocks, round a dogleg. Through another tunnel with a blast of chlorine. A delivery van idling and a black man with a white bag of laundry. A sudden smart glass doorway: ‘Lotus Club’. Under an archway into a courtyard I glanced up and saw a naked stone woman holding a bunch of grapes in each armpit. We went beneath a long brick arch and suddenly we were out on a walkway, a building above and behind us, the river below, and a big black-and-white sign on the railing: ‘Three Cranes Walk’.

The man glanced at me, then turned and was off without looking back again, left right left right with his briefcase slapping against his leg.

‘Thanks,’ I called, but it was too late.

Three Cranes Walk was at the foot of a massive office building. Behind me, pressing down, was the blank bulk of the building. You could imagine someone insisting, there must be public access. Oh, okay, they’d have said, and added this narrow thoroughfare to the plans. Beyond the railing, a wall dropped away sheer to a black muddy beach affair. Beyond that the river ran sulkily under the low grey sky.

There was a bad feeling here, as if you were right on the edge of a cliff. I hung onto the metal railing, feeling it cold under my hands. The air was full of the constant roar and hum of air conditioners, the thrum of a building working at full blast.