There were a few pitiful belongings by the dead man’s side. A black rubbish bag secured by an elastic band holding his worldly goods. A woollen cap still full of coins. And a musical instrument. A thin piece of black wood with a complicated tangle of silver metal buttons and keys.

‘A clarinet?’ I said.

‘Not a clarinet,’ Mallory said. ‘Too small. An oboe.’

‘Nobody’s busking is that bad,’ said one of the SOCOs.

Nobody laughed.

Mallory’s gaze took in the bloodied body, the untouched money, and the musical instrument. He shook his head with what looked like real sadness.

‘Looks like he was on the streets for a while,’ I said. ‘Plenty of addicts and former addicts around Soho. But the homeless don’t often kill each other.’

‘No,’ Mallory agreed. ‘It’s the people with homes to go to who are the problem.’

I looked back at the street. The SOCOs moved in slow motion now, plodding white ghosts, falling into their routine of photographing footprints, gathering cigarette butts, collecting fibres, prints, and samples of blood. One of them was drawing a sketch. The photographer stopped taking stills and started filming the scene. The usual crop of small numbered yellow markers were blooming on the ragged ground and the SOCOs trod carefully between them, like scientists tiptoeing through the aftermath of nuclear Armageddon. Beyond them, in the festive swirl of the blue lights of our cars, uniformed officers were pushing back the crowds recording the drama on their phones.

‘They think we’re putting on Les Misérables down here,’ Mallory sighed. ‘This is a strange space, isn’t it?’

I lifted my head. Mallory was right. It was not really an alley at all, more of a crevice between two of the grand old theatres of Shaftesbury Avenue. At the end of the alley, above the heads of the gawping crowd, I could see the bright lights of the very heart of the city. The white neon of the theatre marquees, the reds and golds of Chinatown.

‘And nobody heard a thing,’ Mallory said, reading my mind.

‘Because his trachea had been cut,’ I said. ‘No windpipe, no scream.’

As the crowds were moved to the far side of the street their voices rose in protest. They craned their necks for a better view and held their little phones even higher above their heads.

‘God spare us from stupid people with smartphones,’ Mallory muttered.

The SOCOs began to erect a tent over the dead man to shield the scene from the public and to protect the thousand tiny scraps of evidence from the weather. Mallory’s gaze settled on the beanie cap full of coins, then moved on to the musical instrument.

‘What kind of heroin addict busks with an oboe?’ he said.