‘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.