‘Now Monk’s returned to the place you go when you’ve run out of places to go,’ Whitestone said. ‘He’s finally come home.’

In the shadow of Olympic Park, a dozen armed response vehicles surrounded a shabby block of flats that managed to be both modern and derelict. They were out of place in a neighbourhood where the buildings were either neat little flats and small houses that promised a nice life in the new East End, or they had been wiped from the face of the Earth. It looked like the surface of the moon after a few years of serious gentrification.

We lowered the windows of the X5 and dug out our warrant cards. Beyond the police tape you could hear the digital cackle of the Airwave radios, the occasional bark from one of the police dogs, and the shouts of officers who were pulled tight by nerves.

Armed officers waited between the ARVs, their Heckler & Koch assault rifles held at their favourite forty-five-degree angle, butt high and business end pointing down, sweating hard in all that kit despite the chill of the December night. They looked like the future.

Tom Monk was standing alone on a scrappy patch of grass outside the block of flats, looking up, his gaze unswerving. And I saw now that there were half a dozen Glock 17 pistols pointing at the back of his head.

They had evacuated most of the residents from the flats. In almost every window the only signs of life were the fairy lights of Christmas, twinkling, white and red and green.

A young woman appeared briefly in one window, a toddler under her arm, and then she was gone. But Monk kept looking up at her window, even after the light in the room had gone out.

‘That’s her,’ said Edie Wren, and the tears on her face shone bright in the riot of flashing blue lights. ‘That’s Monk’s family. That poor girl. That poor man.’

‘No,’ DCI Whitestone said. ‘That’s our killer. Let’s nick the bastard.’

The armed officers stood aside as the K9 unit came forward with their German Shepherds. The handlers knelt by the flanks of their dogs, fingers scratching the back of those noble heads, whispering their final words of encouragement.

Monk turned at the sound of the dogs. His old army coat swung open and I saw his weapon sticking out of the lining, stuffed inside what looked like one of those big secret pockets that shoplifters use – the 12-bore shotgun that he had carried all the way from Potter’s Field.