Quite a bit of that evidence was on display inside the barn itself, when she went in there. The centrepiece was a purpose-built pit, squarish in shape, about ten yards by ten, dug to a depth of five feet and lined with brick, with a steel ladder fixed in one corner and a camera mounted on a tripod overlooking it, alongside an upright chalkboard scribbled with betting information.

Two dogs still occupied the pit. One, an American pit bull, charged crazily back and forth, jumping up to snap and snarl at the officers, despite the excessive blood dabbling its jaws and jowls. The other one, whose breed was uncertain, lay in a quivering, panting heap, gashed and torn and spattered with gore.

‘We need one of the vets in here,’ Lucy said to a PC at her shoulder. ‘And a handler … to control the other one, yeah?’

The PC moved away, just as acting DC Tessa Payne, a young black officer, formerly in uniform but currently on secondment to Crowley CID as a trainee, leaned in through a doorway connecting to another outbuilding. Like Lucy, she only wore light body-armour over her jumper and jeans and was in the process of pulling off her protective gloves and replacing them with latex.

‘Lucy …’ she said. ‘You might want to look in here.’

‘This going to make me throw up?’ Lucy said.

‘More likely make you dance a jig.’

Lucy went through into what was a basically a lean-to shed lit by a single electric bulb, its damp walls lined with shelves groaning beneath the grisly accoutrements of dog-fighting. She saw piles of spare muzzles and harnesses, stacks of grubby second-hand magazines with grotesque images on their covers, homemade DVDs, DIY veterinary kits, including staple-guns and tubes of superglue, and a number of ‘breaking sticks’, thick wooden bars impressed with toothmarks, which would normally be used to pry open a victorious animal’s jaws when it had them locked into its latest victim.

‘Perfect,’ she said. ‘Bloody perfect. All this needs bagging and tagging, Tessa.’

Payne nodded, at which point they were distracted by the sound of more canine whining. The outhouse had its own outer door – again just a frame with no actual door in it. On the other side they found an enclosed yard containing a set of weighing scales, a treadmill and a large glass tank, very grimy and filled to the brim with water so filthy and green that it was almost opaque. There was also a row of grillwork cages with crudely built kennels attached. Each was occupied by a dog, but these were animals of a different ilk to those they’d seen so far. They were highly subdued, lying still with ears flat, each one watching the humans beyond their cages with fearful intensity.

And it was clear why.