‘Such a noisy thing, isn’t he?’ said Mrs Palmarron as she poured the tea.

Now that Toby was relatively quiet I had a chance to notice that there was a lack of dogness about Mrs Palmarron’s flat. There were photographs of, presumably, Mr Palmarron and their children on her mantelpiece, but no chintz or doilies. There was no dog basket by the fireplace, and no hair ground into the corners of the sofa. I got out my notebook and pen.

‘Is he yours?’ I asked.

‘Lord no,’ said Mrs Palmarron. ‘He belonged to poor Mr Skirmish, but I’ve been looking after him for a little while now. He’s not a bad chap when you get used to him.’

‘He’s been here from before Mr Skirmish’s death?’ asked Nightingale.

‘Oh yes,’ said Mrs Palmarron with relish. ‘You see, Toby’s a fugitive from justice, he’s “on the lam”.’

‘What was his crime?’ asked Nightingale.

‘He’s wanted for a serious assault,’ said Mrs Palmarron. ‘He bit a man. Right on his nose. The police were called and everything.’ She looked down to where Toby was chasing rats in his sleep. ‘If I hadn’t let you hole up here it would be the pokey for you, my lad,’ she said. ‘And then the needle.’

I called Kentish Town nick who put me through to Hampstead nick who told me that yes, there had been a call-out to a dog attack on Hampstead Heath just before Christmas. The victim had failed to press charges, and that was all there was in the report. They gave me the name and address of the victim; Brandon Coopertown, Downshire Hill, Hampstead.

‘You put a spell on the dog,’ I said as we left the house.

‘Just a small one,’ said Nightingale.

So magic is real,’ I said. ‘Which makes you a … what?’

‘A wizard.’

‘Like Harry Potter?’

Nightingale sighed. ‘No,’ he said, ‘not like Harry Potter.’

‘In what way?’

‘I’m not a fictional character,’ said Nightingale.

We hopped back in the Jag and headed west, skirting the south end of Hampstead Heath before swinging north to climb the hill into Hampstead proper. This far up the hill was a maze of narrow streets choked with BMWs and Chelsea Tractors. The houses had seven-figure prices, and if there was any quiet desperation here then it had to be over the things that money couldn’t buy.

Nightingale parked the Jag in a residents-only bay and we walked up Downshire Hill looking for the address. It turned out to be one of a row of grand Victorian semidetached mansions set back from the north side of the road. It was a seriously buff house with gothic trim and bay windows; the front garden was professionally cared for and judging from the absence of an intercom, the Coopertowns owned the whole thing.