Dartmouth Park, where William Skirmish had lived, was on the lower slopes of Highgate Hill and within easy walking distance of the Heath. He’d had the ground-floor flat of a converted Victorian terrace, the corner house of a tree-lined street that had been traffic-calmed to within an inch of its life.

Further downhill was Kentish Town, Leighton Road and the estate where I grew up. Some of my school mates had lived around the corner from Skirmish’s flat, so I knew the area well.

I spotted a face in a first-floor window as we showed our cards to the uniform guarding the door. As in many converted terraces, a once elegant hallway had been walled off with plasterboard, making it cramped and lightless. Two additional front doors had been jammed side by side into the space at the end. The door on the right was half-open but symbolically blocked with police tape. The other presumably belonged to the flat with the twitching curtains upstairs.

Skirmish’s flat was neat, and furnished in the patchwork of styles that ordinary people, the ones not driven by aspirational demons, choose for their homes. Fewer bookcases than I would have expected from a media type; many photographs, but the ones of children were all black and white or the faded colour of old instamatic film.

‘A life of quiet desperation,’ said Nightingale. I knew it was a quote, but I wasn’t going to give him the satisfaction of asking who’d said it.

Chief Inspector Seawoll, whatever else he was, was no fool. We could tell that his Murder Team had done a thorough job — there were smudges of fingerprint powder on the phone, the door handles and frames, and books had been pulled off bookcases and then put back upside down. The last seemed to annoy Nightingale more than was strictly appropriate. ‘It’s just carelessness,’ he said. Drawers had been pulled out, searched and then left slightly open to mark their status. Anything worthy of note would have been noted and logged into HOLMES, probably by poor suckers like Lesley, but the Murder Team didn’t know about my psychic powers and the vestigium of the barking dog.