Whittaker was right behind Anderson, and put his hand out to stop himself becoming part of the pile-up. Porter ignored Anderson’s comment and looked through the doorway. Mike Gibson’s body lay just beyond the frame, his feet no more than twelve inches past the threshold. He had fallen with his head turned away from them so Porter couldn’t see his face. A crimson halo surrounded his head, his hair, greying but still with a sprinkling of the dark brown it used to be, now had a liberal splash of red at the base of his skull. One arm lay flat against his body, the other tucked underneath. Porter looked back at Anderson, who just shook his head.

They stood like that for a moment, not meeting each other’s eye.

‘What happened?’ said Porter finally.

Anderson gave them a rough and ready account of what had happened at the warehouse, and how they had ended up here. He explained how they had been waiting in their cars when they heard Gibson shouting, and how he and Simmons had already disappeared inside the building by the time they rounded the corner.

‘By the time we got inside it was all over. Bolton was gone, the other guy, Stenner, had already shot off in the car, and Carter was roadkill. We heard a car start up somewhere out back, but it was gone before we got out there. Found Gibson exactly where you see him. The paramedics checked him for a pulse but …’ His voice tailed off.

‘What about Simmons? Where was she?’

Anderson pointed to the floor just shy of the doorway. ‘She was in a heap on the floor. From the looks of it she’d cracked her head on the doorway’ – Porter saw the dark red stain on the frame where she must have connected with it – ‘and she fell backwards out onto the landing. Think she might even have tripped up on Gibson.’

‘What makes you say that?’ asked Styles, finding his voice for the first time since entering the building. It would be embarrassing for Simmons if that was how it had gone down. Whether it would have made a difference to the outcome for Gibson was debatable, but had her clumsiness meant that a suspect in the death of a police officer had been able to flee the scene?

‘Her foot.’ Anderson gestured with his hand towards where Gibson lay. ‘It was in between where his legs are now, slightly under the material on his trousers by the ankle. She was lying back here, mainly on the landing.’ He gestured back through the door towards the stairs. ‘I’m thinking she heard whatever happened to him, came up fast and came a-cropper.’ He pointed at the door frame. ‘Position of the mark on the frame is consistent with her height.’

‘And what exactly happened to him?’ asked Porter.