‘Ah, the fourth side of the church was known as the Black North because it was always out of the sun. It was reserved for suicides and murderers, who were denied Christian burial rites. Those poor souls were condemned to the darkness, both literally and spiritually.’ The professor pursed his lips as he looked at Cooper. ‘Normally, a funeral procession would enter the churchyard from the eastern gate and follow the direction of the sun to the newly dug grave. On the other hand, a murderer or suicide would be brought in at the west gate and carried against the sun.’

Robertson lifted his shoulders and let them drop again, as if shrugging off any personal responsibility for such practices. But Cooper was thinking of the dark woods in Ravensdale, the dripping canopy of ash trees, the dank moss coating everything, never drying out because it was hidden from the sun.

‘Do you have a complete skeleton?’ asked the professor suddenly.

Cooper was startled. ‘Why do you ask?’

‘It could be significant.’ Robertson smiled. ‘That’s what detectives say when they’re interviewing a witness, isn’t it?’

‘On TV it is, anyway.’

Robertson’s face changed, but he hid his expression behind his whisky glass.

‘There are some bones missing,’ said Cooper. ‘It may mean nothing, though. The forensic anthropologist’s report suggests the activity of scavengers.’

‘It’s quite possible. But if you’re thinking along ritual lines, you should bear in mind that there have been many different attitudes to death, and some of our ancestors’ practices have caused problems for archaeologists.’

‘Problems?’

‘Animals and birds do tend to carry off the smaller skeletal parts, so it was usually only the larger bones that survived excarnation – that’s the technical term for leaving the corpse out in the open air. But after the animals and birds had taken their pick, the long bones and skull were often taken for use in ceremonies.’

Robertson looked at him expectantly. When Cooper asked the next question he felt as though he was responding to a cue, like one of Pavlov’s dogs.

‘What kind of ceremonies?’

‘Any ceremony in which it was useful to have the assistance of one’s dead ancestors. Skulls are considered particularly powerful. But other bones have their significance, too. They relate to the continuing influence of ancestral spirits.’

Robertson stood up and walked to the window, clasping his hands behind his back and staring at the ground like an Oxford don in his college quad.

‘You must think about death quite a bit, sir?’ said Cooper.

But the professor just laughed, his mouth opening wide to show strong teeth and a glimpse of a moist tongue.

‘Try reading Ecclesiastes.’

‘Sir?’

‘Old Testament, dear boy. “As one dies, so does the other. They all have the same breath, and man has no advantage over the beasts. All are from the dust, and all to dust turn again.”’