I didn’t know what this last part meant, but I was too preoccupied with the rest of what Pierce had said to pick up on it. Quin, working with the police? His image had a wide stripe of anti-establishment idealism, coloured by tech-industry optimism: giving people the tools to get around the Man, direct democracy, that sort of thing. During one of the surveillance scandals he had been on Channel 4 News to say that he would never give user data from Roamero or Tamesis to the police or GCHQ. They hadn’t asked, but Quin had seen a public relations opportunity and seized it with both hands. He was on form – articulate, scornful, glowing with righteousness. The only time Cathy Newman managed to wrongfoot him was when she asked how he would feel if criminals exploited Tamesis. The strangest expression appeared on his smooth, innocent face, certainly not an expression one tends to see on these TV interviews: distraction, deep focus, as if he were repeating the question to a deeper part of himself. ‘I can’t imagine how criminals would use something like Tamesis,’ he said at last.

The thought that he could go from that idealistic naïf to being a man designing software for a police drone was staggering. But I was here to interview Pierce.

‘Let’s get back to you,’ I said. ‘What are you working on at the moment?’

‘Not very much, to be frank.’

‘Nothing, really?’

Pierce sighed. ‘Well, there was the grand psycho-concordance of London that ate up so much time and energy. Ever since I abandoned it I have been a bit stuck.’

‘No plans? Ambitions?’ I must sound like Polly, I thought, and that reminded me of her neat list of times and her, if you get a moment, mandatory tasks.

Pierce sighed again, bringing his whole upper body into the action, shoulders slumping – as if the will to go on was visibly deserting him. It was bizarre that the voluble, gossipy creature of a couple of minutes ago should yield to this exhausted, taciturn presence.

‘The encyclopedia was part of a broader project – if you can call it a project, more of an ambition,’ he said. ‘The same project, in fact, as Night Traffic. An attempt to discover something about the city. I don’t know where that project is going now.’

I checked the DVR, but only out of instinct, and watched the seconds climb, recording useless, dud material.

‘So this larger project …’ I began.