‘Five, six? A dozen? Wouldn’t you stand more chance of getting results if you spent your time on some of those? I bet there are people shouting for statements and case files.’

‘Yes, there are. There always are. You know that.’

‘Well, then.’

Cooper was silent. He could see that Fry thought she’d won the argument by sheer, unassailable logic. Budgets, and case loads. Who could argue with those? It wouldn’t be prudent to say what he was thinking right now.

Half an hour later, Gavin Murfin was able to spring a surprise on his colleagues in the CID room.

‘By the way,’ he said. ‘I see Derek Sutton had a criminal record. I found him on the PNC.’

Fry sat up with sudden interest. ‘Oh?’

‘Illegal fuel. He was using laundered red diesel.’

‘A typical rural crime.’

Cooper walked over to Murfin’s desk and looked at the file.

‘A prosecution was brought against Derek Sutton by HM Customs and Excise, following a spot check at the cattle market in Ashbourne. A hefty fine. That was an expensive day out for him.’

Red diesel was normally used in farm machinery, and it was illegal to use it in road vehicles, because it wasn’t taxed. To evade detection, the more enterprising removed the red dye, producing what was called laundered diesel. The Customs and Excise checks would show that up. But Sutton had only been charged with use, not with laundering. He must have known of a source somewhere. Probably everyone did.

‘The Hydrocarbon Oil Duties Act,’ said Fry. ‘“Certain vehicles are exempt from normal fuel duties as they are primarily used off-road and normal road use is only incidental.”’

As always, Cooper was impressed by the efficiency of her mental filing cabinet. He’d almost heard the correct drawer clicking open.

‘Well remembered.’

‘It’s another subsidy for farmers,’ she said. ‘Enshrined in the law, no less. They pay less tax for their fuel than ordinary mortals.’

‘Well, not really. If their farm vehicles never go on the road, they don’t contribute to wear and tear, do they? And they don’t use other facilities on the roads. So why should they be taxed for their maintenance and repair?’

‘You won’t convince me that they don’t go on the roads. I’ve got trapped behind enough farm vehicles to know differently.’

Cooper shrugged. ‘If I recollect the intelligence, Customs have suspected that a diesel-laundering plant might be operating in this area. Do you remember the operation that was closed down in Northern Ireland? It was being run from a converted hay shed at a remote farm.’

‘Like I said, a typical rural crime. These people think they can get away with anything because nobody is watching over them.’

‘You’ve really got it in for farmers at the moment, haven’t you?’ said Cooper. ‘What’s brought this on?’