By the time the snow started at around half six, he was on to the paperwork. Silent flakes, drifting through the light of the sodium lamps above him, beginning to cover up the bloodstains, masking the chewing gum stains and dusting the street in a heavenly but misleading innocence.

Gillard was sitting in his unmarked Vauxhall checking the notation on evidence bags which separately contained: one chunky gold-effect chain (male style, broken), one pair of men’s designer spectacles (broken), a double molar, a torn shirt collar (cotton, male), bloodstained on the inside, and a small folding hunting knife, apparently unused. It could have been worse. He finished the form, checked the time (7.27 a.m.) and suddenly began to fantasise about a bacon sandwich. Two rashers – done crispy – with ketchup, in a brown bap. At this time on a Sunday morning he was unlikely to get any of that around here. But with any luck, he could be back at Mount Browne, Surrey Police headquarters, by the time his shift ended at eight.

The phone call from the incident room changed all that.

A body found at Ashtead Common, just a few miles away. Clear evidence of homicide, and CSI trainee, Kirsty Mockett, a witness, trying hard on her own to secure the crime scene. Gillard vaguely recognised the name.

The operator passed on the puzzling message. ‘She’s asking if you have anything to take a cast of footprints and tyre prints in snow, before it melts.’

Gillard was taken aback, and simply muttered his thanks.

‘I’ll leave that one with you then,’ the operator said, before passing on the exact location.

Kirsty had been expecting the ambulance first, but it was a grey Vauxhall estate which bumped its way the 200 yards down the bridleway towards her. The vehicle stopped thirty yards away and the man who emerged, tall, well-built and exuding capability, was familiar. She remembered DCI Gillard from the applied forensics module, when he had given a talk about dealing with bloodstains. Then he had been wearing a suit, but now he looked rugged in bomber jacket, jeans and hiking boots. His smile of greeting was just what she wanted to see. Her relief was so intense that her eyes watered, and she let a single sob escape before masking it with her hand.

‘I’m so glad to see you, sir,’ she said.

‘We’ve met, haven’t we?’ Gillard said offering his hand. After a quick introduction she began to tell him of all the difficult issues encountered: the cyclist, the dogs, the snow, and all the damage to the crime scene that she couldn’t prevent. She felt she was babbling, but he listened carefully and nodded before turning to her. ‘I got a big bag of ice in the rucksack, it was the best I could do this time on a Sunday morning. The publican at the last crime scene helped me out.’

Kirsty led Gillard through a small scattering of bystanders and their short-leashed dogs, to within five yards of the body. It had been covered with a plastic dry-cleaning bag, weighted with a couple of stones. There was a small mound of snow nearby. But elsewhere, the underlying green of grass was visible through the slush. Only in the shadow of the trees, ten yards further on, was the snow still an unbroken white.