Aidan’s eyes lit up. ‘Something watchful about her, like she couldn’t relax. I was sitting at a table with my brother, and she was at the bar, and clearly didn’t know anybody. I called Guy, the manager, over and asked what she was drinking and he told me soda water. So I asked him to get her in a vodka and soda on me.’

‘Did he tell her what was in it?’

‘I don’t know, but he did say it was from me. I saw her stare at me in the mirror behind the bar, and take a careful sniff of the drink. Very wary, she was.’

‘Professional, perhaps.’

‘No doubt. She didn’t drink it, except a little sip. Ordered another soda water, switched the glasses when she thought I didn’t see, and drank that.’

‘What else did you learn from her?’ Gillard asked. It was a rare treat to be offered an insight into undercover policing from the other side. The other guy knew it, too, and was enjoying telling the tale.

‘Guy told me that she had described herself as a saleswoman, but I never believed it,’ Aidan said.

Gillard wondered quite why this construction worker would care so much.

‘Anyway, it’s all above my pay grade,’ Aidan said. ‘I just dig holes for a living, and keep my head down.’

Gillard nodded towards the digger. ‘So, have you any idea whose body this may be? Ever lost a member of the crew?’

‘Nope. Not one of ours.’ He shoved his hands in his pockets and gave a little smile, as if there was a joke Gillard wasn’t getting. He followed Aidan’s gaze, towards an animated conversation between the two water company officials. They were maybe forty yards away, but it was clear that Arrowsmith, the smaller but more senior of the two, was berating Collier for something.

Not one of ours, Aidan had said. But maybe one of theirs. The missing Ozzy Blanchard, perhaps.

Gillard left the CSI crew and the uniforms to do their job. It was fairly clear from the poor condition of the body that this was not going to be an easy ID job. Dr David Delahaye, the Home Office forensic pathologist, would be down in an hour, but Gillard wasn’t expecting too much. Purely based on the photos Craig had emailed him, Delahaye had warned that it was likely that he couldn’t shed much light on cause of death, and suggested that it would be good to get not only a forensic archaeologist, but the county archaeologist too, who could give some clues as to whether this was a historical death.