‘And we picked up everyone. There was no difference between them when they were lying broken on the ground. Whatever their god, whatever their flag, whatever their uniform, they all looked the same when they were broken. And then one day in Kosovo we picked up a solider of the Serb Volunteer Guard. They were also known as Arkan’s Tigers. Did you ever hear of Arkan?’

‘A paramilitary leader.’

‘His real name was Željko Ražnatović. And we took this wounded Tiger to a house where there were wounded men from every flag, from every god. And of course we did our best to save him. And then Arkan came and we hid the Muslims in the basement because we did not know what might happen to them. And Arkan thanked us and said, “Do your best to save my Tiger.” And Arkan said, “Do you need anything?” And we said, “We need everything. We need everything.” And Arkan came back with three lorries of medical supplies. And that helped us to save many lives.’

‘And did the Tiger die?’

He seemed surprised by the question.

‘I don’t remember,’ he said. ‘But this boy reminds me of that time. What does he need? He needs everything. Because he is a boy who has nothing.’

There is a corner of the Black Museum in New Scotland Yard that is dedicated to the family firms that ran London half a century ago.

Reggie and Ronnie Kray.

Charlie and Eddie Richardson.

Paul and Danny Warboys.

The exhibit features the electrical generator that the Richardsons relied on for extracting confessions, the bolt cutter the Warboys enlisted for removing a talkative lawyer’s tongue and a crossbow that the Krays were planning to use in an assassination. But your eyes drift past these dusty items to the black-and-white photographs behind them.

Reggie and Ronnie sharing a cup of tea in an East End parlour with flowered wallpaper. Charlie and Eddie posing outside the main gates of their South London scrapyard. And Paul and Danny grinning and raising flutes of champagne in one of their Soho nightspots.

It feels like a lost world, that criminal aristocracy of Sixties London – all smart suits and skinny ties and noses that had been broken in the boxing ring, tight bands of brothers with their hair cut short and neat, a leftover from the last generation to do National Service. And the last of the celebrity criminals, pictured in all their swaggering pomp shortly before getting sent down for some of the longest sentences ever handed out at the Old Bailey.

‘You’ll not find him up there,’ said a voice behind me. ‘Steve Warboys never made it to this place.’

I turned and gratefully took a mug of steaming tea from Sergeant John Caine, the keeper of the Black Museum – or, to give it the official title, the Crime Museum of the Metropolitan Police.

‘Hit a brick wall, have you, Max?’

I smiled at him.