Despite her fuzzy head, Anna observed that Henson’s assistants worked as a tight unit. He never had to give an order and while they were doing the weighing and blood tests, he could concentrate on the corpse’s head.

As Henson probed Melissa’s eyes, Anna’s view was obliterated. Without looking back, Henson addressed the room. ‘Well, she’d had severe haemorrhaging, which is usual for strangulation and we still have a veritable feeding frenzy in her eye-sockets. Nasty little sods.’

Anna focused her mind on trying to assimilate what he was saying, rather than looking down at the sliced-open body. Though the stomach contents had almost brought her to her knees, somehow she was still standing. Henson began the incision to lift the scalp. He sliced from behind the head, then peeled the scalp forwards over the face to expose the skull. At that point an assistant handed him a high-powered, high-speed, oscillating saw to open the skull. Next he was handed a chisel to prise off the skullcap.

So far Anna had managed to stay upright. It had seemingly become easier; the stench had mingled with antiseptic which helped. The sound of the chisel finished her off. Unable to control her retching, she only just made it to the ladies’ toilet in time. Banging past the cubicle door, she gasped for breath. She knelt over the toilet bowl and heaved. After several minutes, when she attempted to stand, her whole body was still shaking.

At the basin she ran cold water and kept splashing and dabbing her face with a paper towel, but every time she stood straight, she felt her stomach heave. The stench seemed to cling to her clothes, her hair and her hands, even though she washed and rewashed them using soap from the dispenser.