Lesley felt that I had failed to understand the full implications of using a tracking device, i.e.: you can hang back far enough to be inconspicuous so it doesn’t matter what plates you have. And if she did have diplo plates she wouldn’t have to pay congestion charge or parking tickets and it would make it fucking hard to arrest her.

‘Does she have diplomatic immunity?’ asked Lesley.

‘I don’t know,’ I said. ‘We could ask Kittredge.’

‘Or we could phone Kittredge now and make it his problem,’ said Lesley. She checked the laptop. ‘Where the fuck is he going?’ she said and tilted the screen so I could see it again – the little dots marking Kevin Nolan’s Transit were heading into Knightsbridge.

Suddenly a luxury car with D plates would have blended in perfectly.

‘Who round here is going to want a van full of dodgy greens?’ asked Lesley. The restaurants in that area generally had their own people to go down to Covent Garden for the best produce.

‘Things are tough all over,’ I said. But our fears for the palates of the diplomats and oligarchs proved baseless as Kevin skirted the west end of Hyde Park and turned up Bayswater Road. When he turned again into a side street I put my foot down and closed the gap. We followed him up a line of deceptively modest-looking terraces until Lesley said, ‘He’s stopping.’ In time for me to find an inconspicuous parking space from which we could keep him in view.

London was mostly built piecemeal and if, like me, you know a little bit of architecture you can see where the initial developers built a string of grand Regency mansions along a country lane. Then as the city ground remorselessly westward a line of neat little Victorian terraced houses was built for those members of the working class that one needed to have close at hand.

Kevin had stopped outside an odd late-Victorian terrace consisting of exactly three houses that abutted the back of a 1930s London brick shopping arcade. I forbore from mentioning this to Lesley because discussion of that sort of thing tends to get her vexed.

‘Here come the greens,’ said Lesley.

Kevin Nolan slouched around to the back of his van, opened the doors and collected the first of the pallets and headed for the front door. Lesley lifted the camera and its telephoto and we watched through the cable link on the laptop while Kevin scrabbled around in his trouser pockets.

‘He’s got his own keys,’ said Lesley.

‘Make sure you get a close-up on the pallet,’ I said. ‘I want to know who the supplier was.’

We watched as he ferried the pallets from the van to the house. Once he’d taken the last one inside, he closed the door behind him. We waited a couple of minutes and then we waited some more.