‘I liked the way you set it up,’ Pierce continued. ‘Using Tamesis.’

‘I didn’t do that,’ I said. ‘That was Quin.’

He hesitated. ‘Yes. But it was a clever idea.’

‘It wasn’t my idea. It was all Quin. He did it without saying anything to me.’

The map lost its power over Pierce. He turned, not looking around at me, but down, away, to the floor, into thought, brow creased.

‘How did Quin know what you wanted to do?’ I asked.

‘I may have spoken with him,’ Pierce said, with a hint of what might have been regret, or even guilt. ‘We’ve been in touch.’

‘Me too,’ I said. ‘He’s been moving us about like pins on your fucking map. And I don’t know why.’

Pierce kept his gaze away from the wall. ‘It’s his map,’ he said quietly. ‘Gather enough data about a person and you can manipulate them, guide their choices, get them doing what you want, and they might not even know.’ He turned towards me, and stared. At first I thought I saw the gleam of tears in his eyes, but if they had been there, they went, he overcame them. ‘What if that’s also true of a city?’

I swallowed, and felt the tightness in my chest. How much dust and smoke had got into my system today? How much of London, as it remade itself?

‘All this time I’ve been wondering why he would waste his time jerking around a nonentity like me,’ Pierce said, and the words might as well have come from me, so closely did they match my thoughts. ‘What if it’s not me, not you? You know’ – again he was at the map, as if compelled, up close, eyes flickering from place to place, hands spread out, caressing – ‘my little plan, the map, the psychogeographical index, it wasn’t just about getting revenge on the psychogeographers, the other novelists. I mean, who gives a shit, really? They’re old, old. It was about … ownership. Taking ownership. Retaking it. The city was slipping away from me, from us all, and I wanted it back. And the same had applied to Night Traffic – trying to own a single moment. Because if I had that, no one else could have the whole. Part of it would always be mine alone.’

‘But it was false.’

He didn’t look at me, but he winced. ‘Well, if it was true, it wouldn’t belong only to me, would it? It would belong to … to the ones who …’ and he trailed away, absorbed in an internal struggle beyond my sight.

I had about a third of the can left, and I drained it. During the journey over, I had discovered a vodka miniature in my pocket, the last survivor of my stealthy office session yesterday. Only yesterday. It was warm.

‘Do you have any mixers?’ I asked. ‘Coke?’

‘Lemon squash?’ Pierce said absently.