‘But you’re with me,’ I said. ‘I’m the police – that makes it official.’

‘Ha,’ he barked. ‘The police? Please, as if. No offence but you people have no idea what’s really going on.’

‘No? What’s really going on then?’

‘Things you wouldn’t believe,’ he said.

‘Who’s that?’ I asked as a skinny white boy in a blue Adidas hoodie emerged from the arches and half ran, half stumbled, off towards the main market. In this weather wearing just a hoodie was a true example of style over brains. He was that skinny that he must have been freezing.

‘That’s our Kevin,’ said Zach. ‘Not too bright.’

‘What wouldn’t I believe?’ I asked.

‘You still on about that?’ asked Zach.

‘You brought it up.’

‘Let’s just say that there are more things in heaven and earth than are dreamt of in your philosophy,’ said Zach. ‘That’s Shakespeare, that is.’

‘Are we talking aliens here?’

‘Don’t be stupid,’ he said. ‘But I did see a unicorn in Epping Forest.’

‘When was that?’

‘Back when I was a kid,’ said Zach – he sounded wistful, like it was a real memory. ‘And there’s a shebeen at the top of a council flat where you can get the best beer and bootleg comedy acts this side of the Hudson River. And there’s a girl that lives on the canal at Little Venice who grows blow under water.’

‘You’re sure it’s not seaweed?’ I asked but I was thinking that Zach was a little too well informed to be your average London wide-boy. Not that I was going to let him know that I knew. The golden rule for policing is always try to know more than any suspects, witnesses and officers of superintendent rank and above.

‘This is magic weed,’ he said. ‘I had a block to sell once and I ended up smoking it all myself.’ It had obviously temporarily slipped Zach’s mind that I was police – happens quite a lot with white guys, I’ve noticed. Can be very useful at times.

Kevin Nolan came back dragging a pair of bin bags behind him. He dropped them near the back of the Transit van. We watched as he pulled a stack of plywood crates off a stack and started emptying the contents of the bin bags into them – it looked like greens to me. His movements were exaggeratedly sloppy and sullen, like a child who’d been nagged into tidying his room.

‘What do you think he’s doing?’ I asked.

‘Late bargains,’ said Zach. ‘You can get a lot of cheap stuff if you wait this late in the day and you’re not picky.’

Kevin, the bin bags emptied, started loading the crates into the back of the Transit van. I didn’t want to be chasing him around town in this weather, so I got out of the car.