Cooper tapped the steering wheel and yawned. People walking back looked at them, but took no notice. Sitting at a service station was different from doing surveillance anywhere else. One person sitting in a car didn’t look unusual, but two people tended to arouse suspicion, especially two men. Residents had been known to dial 999 several times a night to report a suspicious vehicle when a surveillance operation was under way.

He remembered a story Murfin had told him once, about an old lady knocking on the car window and offering him and his partner a cup of tea, because they’d been sitting there a long time and she thought they looked bored. If old ladies could recognize unmarked police cars, then surely no criminal worth his salt would have any trouble.

‘Do you think he might be on to us?’ asked Cooper after a while.

‘Ordinary law-abiding people don’t expect surveillance,’ said Fry.

‘But he’s not an ordinary law-abiding person.’

‘I bet he thinks he is.’

Murfin reappeared, and for once there were no suspicious bulges in his pockets. He got back into his car and moved the other side of Elder’s Nissan so he could see into the passenger side.

Then Cooper tensed. A white van crept slowly past their position with its headlights on. Two men were sitting in the cab, looking left and right as they crawled up to the end of the line of cars and started down the next one. It was an ordinary Ford Transit with no markings, indistinguishable from thousands of others that would be seen on the M1 every day.

‘Did you get the registration?’ asked Fry, noticing the same thing that Cooper had.

‘Yes.’

The van stopped, reversed, and drew in next to Elder’s car. Now Fry and Cooper couldn’t see the Nissan at all.

‘Damn.’ Fry dialled. ‘Gavin, can you make them out?’

‘Yes, I’ve got a good view. Two shifty-looking blokes in a white van.’

‘What are they doing?’

‘The headlights have gone off. Now the passenger is getting out, opening the side door of the van. They haven’t spoken to Elder yet. They’ve hardly acknowledged each other, but it’s definitely a meet.’

Cooper started the engine of the Toyota and fidgeted impatiently. Fry began to get frustrated by even a moment’s silence at the other end of the phone.

‘Gavin? Speak to me.’

‘OK, white van man is getting something out, a package wrapped in plastic, quite long. Elder is opening his door, and the bloke has put the package on his back seat. Hardly a word spoken between them, Diane.’

‘Do you recognize either of the two men?’

‘No, but I’ve seen plenty like them,’ said Murfin. ‘Mostly behind bars. Hold on, they’re back in the van, and the lights are back on. Yes, they’re moving. Elder is starting up, too. What do you want me to do, Diane?’