I was struck once again by his formal, old-fashioned English and I could feel the gap between the courtly, well-mannered country he imagined when he first heard the language coming out of a radio in Hong Kong and the harsher reality he had found in London.

And I believed him – he had not seen the driver and he didn’t have much more to tell us. I could see he felt ill used.

I held out my hand and told him my name.

He shook my hand although his grip was so soft I regretted the gesture.

‘Keith Li,’ he told me, one of the generation of Chinese who had automatically adopted an Anglo name, usually the kind of name that the British had stopped using two or three generations ago.

‘You speak very good English, sir.’

‘In China, I was a teacher.’ He laughed bitterly. ‘In England – nothing.’

I went up to Major Incident Room One.

Whitestone and Edie were wearing blue nitrile gloves and poring over the passports of assorted nationalities in red and blue and green they had spread out before them like a deck of cards.

Trainee Detective Constable Billy Greene was at a workstation, his long, gangly body hunched up as he scrolled through still black-and-white images of vehicles, their number plates showing in yellow and black at the foot of the screen.

And there was a tiny middle-aged man with milk-bottle glasses sitting between Whitestone and Edie who was also wearing gloves, and sliding what looked like a Syrian passport into some kind of clunky silver box. The machine resembled a computer printer from when the world was young. He looked a bit like a mole.

‘Did you talk to her, Max?’ Whitestone said.

I shook my head.

‘The Royal Free are going to call me when she comes out of the ICU. How many more made it?’

‘None,’ Whitestone said. ‘The rest of them were pronounced dead at the scene. It took the Divisional Surgeon quite a while. Apparently it’s hard to tell when they freeze to death. Something to do with the heart rate slowing to next to nothing. So we have eleven dead.’ She tapped a burgundy passport with a golden coat of arms. ‘And Hana Novak fighting for her life at the Royal Free.’

‘So we still have that thirteenth passport,’ Edie said. She nodded at the man with the silver machine. ‘Ken here is from Visas and Immigration at Heathrow.’

‘I’m the Questioned Documents guy,’ Ken told me. ‘Running your passports through my VSC40 here to see how many of them are kosher.’

‘What does the machine do?’

‘It reads microchips, assesses paper quality and scans surface features such as visa stamps,’ he said. ‘It sniffs out fake watermarks, bogus metallic strips and home-made ink.’ He grinned shyly at me, warming to his theme. ‘Basically it’s a lie detector for travel documents.’