I looked across at the lorry. The back doors were open and I could see the blaze of dazzling lights that make every crime scene look like a low-budget film set. As I watched, a body bag was eased out of the back doors, and the tenderness and care of the paramedics who had never known Billy Greene clawed at my heart.

‘What was he like?’ the sergeant said.

I remembered Billy Greene as a young uniformed officer, overwhelmed at the sight of his first murder victim. And I remembered him overcoming his fears, and his natural-born mildness of manner, and I remembered Billy putting himself in harm’s way for total strangers. I remembered the scars on his hands.

I coughed, clearing my throat.

‘He was all right,’ I said. ‘He was a good lad.’

I saw a car blazing blues-and-twos pull up at the perimeter. Pat Whitestone and Edie Wren got out. Edie held up a hand in salute but I looked away.

‘I want to see him,’ I told the sergeant.

He stared at me. This was not my investigation. I was not Billy’s next of kin. The Port of Dover sergeant had every right to tell me to go away.

‘Of course,’ he said.

We walked towards the lorry, towards the convoy of squad cars that surrounded it with their almost festive blue lights, towards the body bag resting by the side of the road.

The other side of the motorway was still open, heavy traffic steaming south for the coast, not moving fast and slowing further with that ghoulish instinct to observe tragedy. Their hand-held devices covered many of the faces at the windows of the cars and the lorries, and I wondered what possible reason anyone could have to want to look at this scene ever again.

The sergeant nodded at the paramedics and something passed between them, giving me access to my friend without need of explanation, and I knelt by the bag and inhaled deeply, not tasting the sea any more, just the diesel fumes of the motorway and the dead winter fields beyond.

We don’t call it a body bag. We call it an HRP – Human Remains Pouch – and although the movies like to show them as heavy black rubber jobs, the reality is different. The HRP that held Billy was white plastic with webbing handles and a black zip running the length of it, which I pulled down briskly before I had a chance to think about it too much and change my mind.