There were signs everywhere bearing the same message: ‘You are about to enter an area where hazardous activities take place.’ He was warned to watch for red flags flying to indicate danger.

A dark strip of woodland separated the Health and Safety testing grounds from some University of Sheffield laboratories on the western side. The Department of Civil and Structural Engineers, the Communications Research Group and CEDUS. What was that? Cooper couldn’t remember what the initials stood for, but he had a feeling it was to do with research into the blast effects of high-velocity explosives.

Hurst began to cast about like a terrier sniffing the ground for a fox. Murfin made a desultory show of peering through the windows of an abandoned building.

‘I hear you’ve been talking to Brendan Kilner,’ said Murfin, without turning round.

Cooper stared at him. He hadn’t mentioned his conversation with Kilner or his visit to Buxton Raceway. But he tended to forget how long Gavin Murfin had been in this job and how many people he knew. Gavin’s network of informants must be pretty extensive by now. No doubt someone in the crowd at Axe Edge saw him talking to Kilner and mentioned it to Murfin in the pub last night. He ought to have known that was a possibility.

‘He can be useful,’ he said.

‘Kilner is a lifelong criminal,’ said Murfin. ‘A born scrote. He probably mugged the midwife before he was five minutes old. These days they say he’s into the drugs trade because it’s more profitable.’

‘It doesn’t mean he can’t be useful for providing a bit of information, Gavin. You know that. Don’t be so cynical.’

Murfin grunted and kicked at a lump of broken concrete. ‘So you think it’s okay to spend your time with the bad guys?’

‘If it’s necessary. Now can we get on with it, Gavin?’

‘Just so we’re clear.’

The whole site was scattered with concrete bunkers, chimneys, ventilation shafts and scaffolding structures emerging from the ground, a CCTV camera on a gantry watching for walkers getting too close. A drop tower and old bomb stores. He passed Bunker 90. Further on the red flags were fluttering at half-mast. So no danger at the moment.

Ahead were the large main buildings, looking like any other modern office complex. They made the rest of the site seem like a vast playground filled with tunnels and towers, railway tracks and climbing frames, and places where you could just make things go bang. The high explosive testing tunnel ran for about a quarter of a mile across the site and was said to contain the scorched remains of a headless test dummy, still perched in a blackened chair in the path of an explosive blast.

Cooper produced a print of the photograph of the group taken on Sandra Blair’s phone.

‘About here, perhaps?’ he said.

Hurst squinted at the picture and the landscape in front of them. ‘Could be.’

Somewhere over there to the west the HSE had brought in some disused London Underground trains for testing after the 7 July bombings in the capital, when forty-two people were killed by bombs on the Tube in 2005. The carriages had been subjected to test explosions in a makeshift tunnel. As a result of the testing a series of burned-out Jubilee Line units with their windows and doors blown off had stood around the site for years, only a couple of hundred yards from a public footpath through the old RAF base.

They were on one of the public footpaths now, probably the one walked by Sandra Blair’s group. Becky Hurst pushed open the broken door of a concrete shed, which revealed a stack of old drums of Shell Tellus Oil.

‘What is that?’ she said.

‘Hydraulic fluid. That’s all.’

It was strange that the HSE had made no attempt to divert the footpaths, the way Deeplow Quarry had done. Instead, they had installed CCTV cameras and warning signs, and red flags to indicate when an explosion was imminent. They also recorded use of these footpaths, and the HSE’s security teams had sometimes asked people to leave. B Division response officers were occasionally despatched to make sure that suspicious individuals had actually departed the site.

Hurst had reached a fence and worked her way along to a stile that led over the hill towards the far side of the site.

‘I wonder where that track goes from here?’ she said.

There was no need to consult the map this time. Cooper knew the answer perfectly well. He could picture the funeral party picking their way carefully down this hill, a coffin shifting precariously on their shoulders as the slope became steeper. He was able to imagine the weary sighs as they halted at the gate a hundred yards below him on the hillside, resting the coffin on the large, flat stone until the relief bearers took it up again.

‘We know where it goes,’ he said. ‘It comes out at the Corpse Bridge.’

32

Villiers and Irvine had left Jason Shaw’s cottage in Bowden and were driving back towards Edendale.

‘Did you hear that?’ said Villiers. ‘He offered us a suspect in Sally Naden, then said himself how ridiculous an idea it was.’

‘Not very helpful.’

‘Deliberately unhelpful.’

When they got back to West Street, Ben Cooper was out of the office. He’d disappeared, taking Becky Hurst and Gavin Murfin along with him.

‘What do we do now?’ said Irvine, turning to Villiers.

Villiers grimaced and nodded across the office. ‘You know there’s only one thing we can do, Luke,’ she said. ‘We have to report to DS Fry.’

Molly Redfearn had returned from Paris that morning. Diane Fry had taken over the interviews with the victim’s wife and was writing up her report when Irvine and Villiers came in.

Mrs Redfearn had been just the sort of woman Fry disliked most – cold, middle class and materialistic. Exactly the kind of woman she was afraid of turning into herself, in fact.

The perfume Molly Redfearn was wearing had been almost overpowering. Fry had been glad that they weren’t talking to each other in one of the interview rooms at West Street, with their archaic lack of ventilation. They would all have been stifled and found dead in their chairs an hour or two later.

But the results of her interview were disappointing. Mrs Redfearn had been out of contact with her husband throughout the whole of her trip to Paris with her girlfriends.

When she saw Irvine and Villiers approaching she willingly put her half-finished report aside to listen to what they had to say.

‘So that’s his story,’ said Irvine when they’d finished. ‘He basically put the blame on everyone else.’

‘And there was no one on the bridge with Mrs Blair that night?’

‘Not according to Shaw. He admits taking her there with the effigy and all that stuff, but then he left her to it.’

‘And what do you think of that, Luke?’ asked Fry.

‘I think he’s telling only half the truth again.’

Fry looked at Villiers, who agreed.

‘His attempt to blame Sally Naden looks a bit weak, but you can never tell.’

‘No.’

Fry was interested in Jason Shaw’s job as a gamekeeper. She would have to get a check done on the firearms register.

She looked up at Irvine and Villiers.

‘By the way,’ she said. ‘Do you know where DS Cooper is?’

On the far side of the Harpur Hill testing grounds Cooper realised how close he was to Buxton Raceway. There was no race meeting today, but he could see the circuit and the stand where he’d talked to Brendan Kilner. It was Kilner who pointed him in the direction of the graveyard, yet here he was coming full circle within thirty-six hours.

He’d left Becky Hurst and Gavin Murfin checking their way through the old buildings, the former RAF bunkers that had been abandoned or even demolished. They would be grumbling to each other by now. They might not appear to get on, but they’d developed an understanding. Hurst respected Murfin’s experience, though she would never have said so, and Gavin wouldn’t have wanted her to.