‘Seventeen,’ said James. ‘I’m top of my class with a grade point average of 4.8, and I’m confident I’ll do well in my SATs.’ He paused before adding, ‘Should I presume you made it to Scotland Yard, Chief Inspector?’

‘Yes,’ William came back. He was used to being interrogated by leading counsel, not teenagers, although he was enjoying the encounter. ‘But if you’re that bright, why haven’t you considered becoming a lawyer, or going into politics?’

‘There are far too many lawyers in America,’ said James with a shrug of the shoulders, ‘and most of them end up chasing ambulances.’

‘And politics?’

‘I wouldn’t be any good at suffering fools gladly, and I don’t want to spend the rest of my life at the whim of the electorate or allowing focus groups to dictate my opinions.’

‘Whereas, if you were to become the Director of the FBI …’

‘I would be my own master, answering only to the President, and I wouldn’t always let him know what I was up to.’

William laughed at the young man, who clearly didn’t suffer from self-doubt.

‘And you, sir,’ said James, sounding more relaxed, ‘are you destined to become the Commissioner of the Metropolitan Police?’ William hesitated again. ‘Clearly, you think it’s a possibility,’ James continued before he could reply. ‘May I ask you another question?’

‘I can’t imagine what would stop you.’

‘What do you consider are the most important qualities needed to be a first-class detective?’

William gave the question some thought before he responded. ‘A natural curiosity,’ he eventually said. ‘So you immediately spot something that doesn’t feel quite right.’

James took a pen from an inside pocket and began writing William’s words down on the back of the Alden Daily News.

‘You must also be able to ask the relevant questions of suspects, witnesses and colleagues. Avoid making assumptions. And above all, you have to be patient. Which is why women often make better police officers than men. Finally, you must be able to use all your senses – sight, hearing, touch, smell, and taste.’

‘I’m not sure I fully understand,’ said James.

‘That must be a first,’ William replied, immediately regretting his words, although the young man laughed for the first time. ‘Close your eyes,’ said William. He waited for a moment before saying, ‘Describe me.’

The young man took his time before replying. ‘You’re thirty, thirty-five at most, a shade over six foot, fair hair, blue eyes, around a hundred and seventy pounds, fit, but not as fit as you used to be, and you’ve suffered a serious shoulder injury at some time in the past.’

‘What makes you think I’m not as fit as I used to be?’ said William defensively.

‘You’re about six or seven pounds overweight, and, as this is the first day of the voyage, you can’t blame the never-ending meals they serve on board ships.’

William frowned. ‘And the injury?’

‘The top two buttons of your shirt are undone, and when you leant forward to shake hands, I noticed a faded scar just below your left shoulder.’