‘It isn’t so long ago that the NCIS bulletins were warning of cash machine gangs spreading out of London down the M4 to the West Country. Did they get it wrong?’

‘No, not at all. Those gangs did good business in the West Country, so they decided to go nationwide. Now they operate in any place they can recruit enough illegals.’

‘Illegals?’

Cooper could hear a few sets of antennae going up, alert for derogatory remarks. It was always a tough call, knowing when to report a colleague for political incorrectness. If you tolerated it, your own career could be on the line.

But PC Judson seemed not to have noticed the reactions from the group.

‘Some illegals are being trained for cash machine work within twenty-four hours of coming off the boat. That way, they can pay back the traffickers. It’s better than slogging your guts out in a carrot field in East Anglia for two quid an hour, I suppose.’

Nobody laughed, or even dared to nod in agreement. A Nottinghamshire detective next to Cooper shuffled his feet in the shredded tree bark around the roots of an ornamental birch.

Somebody at the front asked a question about identity theft, which set Judson off on a new tangent. The Nottinghamshire officer leaned towards Cooper.

‘Are you Derbyshire?’ he said quietly.

‘Yes, I’m based right here in Edendale. DC Cooper.’

‘Ross Matthews. Hi. What’s it like working here?’

‘It’s OK,’ said Cooper defensively.

Matthews nodded. ‘I’m at St Ann’s, and it’s a nightmare. I might put in for a transfer when we go global.’

He didn’t need to explain what he was talking about. Everyone knew that the number of regional police forces would soon be reduced dramatically. A government commission had concluded that any force with fewer than four thousand officers was too small to deal with serious crime. So Derbyshire was certain to disappear. Even its bigger neighbour, Nottinghamshire, had suffered highly publicized problems that had led its chief constable to admit his detectives couldn’t cope. Within a few months, all the officers here this morning might be working for one huge East Midlands Constabulary.

‘Why not?’ said Cooper. ‘We can always do with some help here.’

He realized that Judson had finished speaking and was looking at him over the heads of the group, waiting for his attention.

It was then that Cooper’s mobile rang. Probably he should have switched it off. He bet everybody else had put theirs on to silent vibrate, but he’d forgotten this morning.

He looked at the number on the display, and saw it was Diane Fry. His DS shouldn’t be calling him, not when she knew he was on the plastic crime exercise. Cooper looked at Judson and shrugged apologetically, then walked a few paces away from the group.

‘Yes, Diane?’

‘Where are you right now, Ben?’

‘Somerfield’s supermarket.’

‘I suppose that makes sense, does it?’