‘Who do you think might have done that, Mr Shaw?’

‘I don’t know.’

‘One of the group?’

‘Like who?’

‘You tell me.’

He shook his head slowly. ‘I honestly can’t imagine. I mean, they didn’t always see eye to eye. They argued sometimes. Particularly…’

‘Yes?’

‘Well, Sally Naden. She didn’t think much of Sandra. I heard her say once that Sandra was a liability. But it wasn’t serious. She would never kill her. Why would she do that? It doesn’t make sense.’

‘It was your suggestion.’

‘I’m just trying to help.’

‘As it happens,’ said Villiers, ‘the post-mortem examination suggests that Mrs Blair wasn’t deliberately killed. She may just have had an accident.’

Shaw looked faintly relieved. ‘Well, even so – it’s still a real shame.’

Irvine cast around for any questions that Villiers hadn’t asked. As usual he found himself wondering what Ben Cooper would do or say. Something a bit unexpected, which might catch their interviewee.

‘You work here at Knowle Abbey, don’t you, sir?’ he said.

Shaw looked at him. ‘I’m on the estate staff. Gamekeeping mostly.’

‘Have you always worked on the estate?’

‘No. I used to have a job in Hartington. It was good work too. But that went belly up.’

Villiers frowned. But Irvine had picked up a thing or two while he was with Cooper.

‘Did you have a job at the cheese factory?’ he said.

Shaw’s entire attention was on him now and it made Irvine smile.

‘Yes, I was in the warehouse,’ said Shaw. ‘I did a bit of forklift work too. You know what happened to the factory, then?’

‘Yes, of course,’ said Irvine, feeling smug. ‘It was sold and you were all made redundant.’

Shaw scowled. ‘That’s the truth. And it’s the same story everywhere you go.’

31

The last time Cooper had been to Harpur Hill was for a match at Buxton Rugby Club’s ground, which claimed to have the highest posts in the country. They often played in appalling weather conditions up here. But then, Buxton was notorious for its weather, ever since a cricket match was interrupted by snow in the middle of June.

The village itself lay between the outskirts of Buxton and the quarries off the A515. A large proportion of Harpur Hill had been occupied for years by the sprawling, derelict buildings of an old University of Derby campus, which had once been High Peak College. After a new campus was created from Buxton’s former Devonshire Royal Hospital, the empty Harpur Hill buildings lay damaged and rotting, like a set of broken teeth, an incongruous lump of urban decay that split an ordinary village housing estate in half.

As Cooper passed through, he recalled that the site had attracted intruders, despite the security fencing. Thieves removed lead from the roofs and stripped out wiring. Once, a large pentagram had been found scratched into the floor of the refectory. Empty buildings were like a magnet for the curious and the opportunist.

DCs Becky Hurst and Gavin Murfin were in the car with him, the only officers available and willing to follow his instinct. He was lucky they hadn’t already been appropriated for other assignments.

At least he seemed to have got Diane Fry out of his hair for the time being. Her attention was on the George Redfearn inquiry, like everyone else – though Cooper had a strong suspicion the results might lead her straight back to him before long.

‘So what’s in Harpur Hill?’ asked Hurst doubtfully as they slowed almost to a halt behind a tractor towing a trailer of manure.

‘Elf ’n’ safety,’ said Murfin. ‘The temple of our new God.’

‘Is it?’ said Hurst. She twisted round to look at Murfin, who was slumped in the back seat. ‘I thought your God worked at the local pie shop.’

Cooper glanced in the rearview mirror. Murfin might well have a pie hidden somewhere in his pockets. He could smell the warm juice now, drifting through the car.

‘You’re just a heathen,’ said Murfin. ‘You wait until Judgment Day. Then we’ll see who gets chosen.’

‘You’re too heavy to float up to heaven,’ said Hurst. ‘You’ll sink the other way.’

Murfin sniffed and maintained a dignified silence for a few moments.

‘And the Blue Lagoon,’ he said suddenly. ‘Am I right?’

‘The what?’ asked Hurst.

‘Yes, you’re right,’ said Cooper.

Directly opposite the old university campus, the flooded Far Hill Quarry had also hit the headlines for a while. For years it had been known as the Blue Lagoon, because of its azure colour, which made it a popular place for swimming. It was also one of the most polluted stretches of water to be found anywhere in Derbyshire.

The attractive colouring had been caused by the surrounding limestone rocks, which leached calcite crystals into the water, turning it turquoise. Its alkalinity came from calcium oxide, a by-product of the quarrying process. The lagoon was known to contain car wrecks, dead animals, excrement and other kinds of toxic rubbish. Despite the signs warning that high pH levels could cause rashes, eye irritations, stomach problems and fungal infections, parents could be seen pulling their babies around in rubber rings on the water. Whole families regularly made the trek to the lagoon, gazing at the blue water as if to convince themselves they were in the Bahamas. It had been beautiful to look at, but horrendously dangerous.

But it wasn’t pretty any more. On the principle that the lagoon’s attraction was all about surface appearance, the council dyed the water black. When they visited Far Hill Quarry now, people didn’t think they were in the Bahamas any more. They knew perfectly well they were in Derbyshire.

‘One of the coffin roads started from somewhere near here,’ said Cooper.

‘Oh.’ Murfin gazed out of the car window. ‘You wouldn’t think you’d died and gone to heaven, would you?’

Hurst laughed. ‘I’m with you there, Gavin.’

Past Hoffman’s Bar, Cooper turned off by the Parks Inn and followed a twisting road that led up to the industrial estate. He found an engineering factory, a pet crematorium, then the gleaming, modern laboratory complex operated by the Health and Safety Executive.

From 1938 the RAF had turned a vast area of hillside above Harpur Hill into a series of underground munitions stores. Tunnels were dug out to house large amounts of ammunition and ordnance, including howitzer shells loaded with mustard gas and phosphorus. When the RAF left, the tunnels were used as a mushroom farm, then as a cold store for cheese, and finally as a warehouse for wines and spirits. Many of the bunkers could still be seen in the surrounding landscape, which was now used as testing grounds for the Health and Safety Laboratory.

Cooper wondered how many health and safety regulations had existed at the time when cheese was stored in the same tunnels that once contained chemical weapons. Local people had all kinds of stories about this place. The number of underground bunkers and mysterious explosions accounted for many of the rumours.

A sign pointed to a half-overgrown path that led down through the trees to a steep hillside and an area of limestone pasture. When Cooper got closer he saw that the sign was for the Buxton Climate Change Impacts Laboratory.

‘It’s an enormous site,’ said Hurst. ‘And there are just the three of us. How are we going to do this, Ben?’

‘Don’t you understand yet?’ said Cooper. ‘We only need to find the route of the old coffin road.’

He was aware of Hurst and Murfin looking at each other when he said that. Murfin gave a subtle shrug. His DCs were loyal, but even they didn’t believe in his theories.

The HSE’s own security teams had been asked to check the parts of the site nearest to the laboratories. But two or three public footpaths ran through the old RAF camp and these were the readily accessible areas. The route of the old coffin road must have followed one of these public rights of way. Sandra Blair’s group must have worked out the route for themselves. Not only did they walk it as a group, but they had their photograph taken around here. Was this the moment when someone suggested taking their protest further?