Th dapper man picked up a penny and turned it over in his fingers, scrutinising it.

"Yes, this is definitely his," he said, after some time.

"How do you know?" his companion prompted, with bemused admiration.

"We know our chap must have had a lucky penny. This one is worn, as if it has been rubbed many times - for luck, you see - but it is still dirty. Our chap is a dockhand; it is grime from his workplace that has become ingrained in the coin. He must have dropped it when he realised he was being pursued."

"How did you know he had a lucky penny?"

The first man gave his companion an indulgent smile.

"He was always reaching in his innermost jacket pocket, holding something tightly and rubbing his fingers against it. His reaction to that black cat showed that he was a superstitious man. It took little effort to make the connection."

"Brilliant, Holmes," the second man said, shaking his head with incredulity, "Just marvellous."