The balcony was L-shaped with a wide section by the living room, for afternoon tea in the sunshine I presumed, and then a much thinner long bit that ran the length of the flat. We knew from the floor plans posted by an estate agent that every single room except for the bathrooms and the kitchen had its own French window onto the balcony and we knew from being coppers that the chance of them being locked, thirty storeys up, was remote. The balcony was less than a third of a metre wide and even with a waist-high parapet I felt queasy when if I let my eyes drift too far to the left. Assuming that the nurse would be in the smaller of the two bedrooms I continued to the end of the balcony which terminated in one of the pressure-door-shaped fire exits. I pulled on my gloves and tried the French windows – they slid open with encouraging silence. I stepped inside.

The bedroom door was open, but the light in the hallway beyond was out and so the room was too dark to see anything. But I wasn’t there to use my eyes. There was a musty sickroom smell overlaid with talcum powder and, weirdly, Chanel number 5. I took a deep breath and felt for vestigium.

There was nothing, or at least nothing obvious.

I wasn’t as experienced as Nightingale but I was willing to bet that nothing magical had happened in that flat since it had been constructed.

Disappointed, I carefully shifted position until I could see out the door, down the length of the hallway and into the dining room where Lesley was still asking her questions. She’d obviously caught Woodville-Gentle’s interest – the old man was leaning forward in his chair, staring at what I realised, with a shock, was Lesley’s uncovered face. Varenka too seemed fascinated, I heard her ask something and saw Lesley’s misshapen mouth frame a reply. She’d joked that as a last resort she could create a distraction by taking her mask off but I never thought she’d do it. Woodville-Gentle reached out a hand in a tentative, gentle gesture, as if to touch Lesley’s cheek but she jerked her head back and quickly fumbled her mask back on.

I suddenly noticed that Varenka, who’d been standing off to the side watching, had turned to look down the corridor and into the master bedroom. I kept absolutely still, I was in shadow and I was certain that if I didn’t move she wouldn’t see me.

She turned her head to say something to Woodville-Gentle and I took a step sideways – out of sight. Score one for the Kentish Town ninja boy.

‘The things I do to keep you out of trouble,’ said Lesley as we rode the lift down to the car park. She meant taking off her mask. ‘Was it worth it?’

‘Nothing that I could feel,’ I said.