I thought about it. ‘One who comes from money. One who had all the chances. One who comes from privilege. The music teacher coming round once a week to practise the oboe. The lessons going on for years. Money never a problem.’

Mallory ran the palm of one large hand over his bald head and then pushed his John Lennon glasses a bit further up his broken nose. ‘Or maybe he just stole it.’ A beat. ‘But I don’t think so. I think you’re right. I think there was all kind of care lavished on him. A long time ago now.’

The flash from a SOCO’s camera lit up a part of the alley wall that the arc lights had not reached. Among the fresh spurts of travel blood there was a tangle of graffiti I had missed. One word shouted at me and I stepped closer to see, although I already knew what it said.

P I G

On the far side of the street I could see perhaps a hundred mobile phones, held above the shoulders of the uniformed officers who stood on the far side of the POLICE DO NOT CROSS tape. The crowds had been pushed right back now but the numbers were growing, stretching our officers, and as their excitement mounted the white lights on their phones glowed like the eyes of wolves in winter.

A SOCO came down the alley, carrying a laptop in one hand and pulling off her facemask with the other.

‘Good body, sir,’ she said to Mallory.

‘No witness, no weapon, no CCTV, no ID and no glove prints,’ he said. ‘I’ve seen better.’

In the morning I took care of my daughter and my dog and then I drove to work – 27 Savile Row, London W1. The Met call it West End Central.

27 Savile Row is a modern block of offices with one of those ancient blue police lamps outside – the kind of blue lamp that makes you think of Sherlock Holmes hunting Jack the Ripper through the London fog. But although Savile Row is famous for two things, West End Central isn’t one of them.

For hundreds of years Savile Row has been home to the most exclusive men’s tailors in the world. The short Mayfair street is also where, on the rooftop high above number 3, the Beatles played their final gig, attracting the attention of the local police. The attending officers from West End Central let the Beatles finish their last ever set because they were all music fans. That’s what they tell you in West End Central.