Despite the tragedy of the situation, Roy Grace knew that when he returned to Sussex, one thing he would miss was the sheer number of officers the Metropolitan Police were able to deploy to a crime scene – and the speed at which they could do it.

Another thing he would miss was having a driver at times like these, he thought. Especially after last night, when he’d had farewell drinks at a pub with his team. He’d grown fond of them all in the short time he’d been in London and would miss them.

Thanking Davey, he started collecting his thoughts about this murder and the day ahead, as he showered and shaved. He needed to be looking sharp for an 8 a.m. breakfast meeting with Alison Vosper – which she had requested, somewhat to his surprise.

He waited downstairs, dressed in his uniform, sipping a strong coffee as he was eyed by a half-awake Humphrey, licking his paws. When he heard the sound of a car pulling up outside, he went upstairs, finding Cleo awake now and sleepily putting on a T-shirt. He apologized for waking her, held her head in his hands and gave her a big kiss. Then he hurried back down, grabbing his laptop and go-bag, and climbed into the back of an unmarked Audi.

Too wired to go back to sleep, he spent the thirty-minute, high-speed, blue-light journey on his laptop, going through the case files of the trial of Dr Edward Crisp.

‘This is as close as we can get, sir,’ his driver announced, bringing the car to a halt.

Grace looked up, surprised they were here already. A street-lit residential road. A couple of low-rise apartment blocks and post-war semis on both sides. Ahead, through the windscreen, he could see a blaze of blue flashing lights, and just beyond, with a uniform scene guard, police tape sealing off the road. It was a hive of activity. A large number of police vehicles, including a marked Transit van and a Crime Scene Investigation truck.

Leaving his laptop on the rear seat, he climbed out with a heavy heart. Every knife-crime murder that happened under his watch he considered to be a failure. A failure down to him.

Opening the boot of the car, he pulled out a protective oversuit, shoes and gloves from his go-bag, wrestled into them, then walked towards the cluster of vehicles and a group of people, mostly youths, hanging around the outer cordon. He showed his warrant card to the scene guard, signed the crime scene log and ducked under the tape.

A short distance ahead was a group of people similarly attired to himself, standing in the glare of temporary floodlights around a tent, the generator powering them rumbling close by. Several POLSA, in blue gloves, were on their hands and knees on the pavement doing a fingertip search, taking advantage of the so-called ‘golden hour’.