‘Listen Toby,’ I said, ‘your master is dead, I’m not a dog person and my governor would turn you into a pair of mittens as soon as look at you. You’re looking at a one-way ticket to Battersea Dog’s Home and the big sleep. Your one chance to avoid the big kennel in the sky is to use whatever doggy supernatural senses you have to track … whatever it was murdered your owner. Do you understand?’

Toby panted and then barked once.

‘Close enough,’ I said, and put him down. He immediately trotted over to the pillar and lifted his leg.

‘I wouldn’t turn him into a pair of mittens,’ said Nightingale.

‘No?’

‘He’s a short-haired breed – they’d look terrible,’ said Nightingale. ‘Might make a good hat.’

Toby snuffled around a spot close to where his master’s body had lain. He looked up, barked once and shot off towards King Street.

‘Damn,’ I said. ‘I wasn’t expecting that.’

‘Get after him,’ said Nightingale.

I was already on my way. Detective Chief Inspectors don’t run – that’s what they have constables for. I sprinted after Toby who, like all rat-like dogs, could really shift when he wanted to. Past the Tesco’s he went, and down New Row with his little legs whirring like a low-budget cartoon. Two years running down drunks in Leicester Square had given me some speed and stamina, and I was gaining when he crossed St Martin’s Lane and into St Martin’s Court on the other side. I lost ground when I had to dodge around a crocodile of Dutch tourists leaving the Noël Coward Theatre.

‘Police,’ I yelled, ‘get out of the way!’ I didn’t yell ‘stop that dog’ – I do have some standards.

Toby whirred past the J. Sheekey Oyster Bar and the salt-beef and falafel place on the corner, and shot across the Charing Cross Road, which is one of the busiest roads in central London. I had to look both ways before crossing, but luckily Toby had stopped at a bus stop and was relieving himself against the ticket machine.

Toby gave me the smug, self-satisfied look employed by small dogs everywhere when they’ve confounded your expectations or messed on your front garden. I checked which buses used the stop – one of them was the 24: Camden Town, Chalk Farm and Hampstead.

Nightingale arrived, and together we counted cameras. There were at least five that had a good view of the bus stop, not to mention the cameras that Transport for London routinely mounts in its buses. I left a message on Lesley’s phone suggesting she check the camera footage from the 24 bus first. I’m sure she was thrilled when she got it.

She got her revenge by calling me at eight o’clock the next morning.

I hate the winter; I hate waking up in the dark.

‘Don’t you ever sleep?’ I asked.