French was quite as excited as she, but he controlled himself and spoke easily.

“Tell me first whose they are and how you are so sure of them.”

“They’re Mr. Pyke’s, what he was wearing the night he was lost. I couldn’t but be sure of them. See here. There’s the wool first. I darned that and I remember I hadn’t the right colour. Then these buttons.” She picked up the vest. “I put that one on. See, it’s not the same as the rest; it was the only one I could get. And then if that wasn’t enough, these are the cuff-links. I’ve seen them hundreds of times and I’d know them anywhere. Where did you get them?”

French dropped his suave, kindly manner and suddenly became official and, for him, unusually harsh.

“Now, Mrs. Billing,” he said, sharply, “I’d better tell you exactly who I am and warn you that you’ve got to keep it to yourself. I am Inspector French of New Scotland Yard; you understand, a police officer. I have discovered that Mr. Pyke was murdered and I am on the track of the murderer.”

The landlady gave a little scream. She was evidently profoundly moved, not only by surprise and excitement, but by horror at her late lodger’s fate. She began to speak, but French cut her short.

“I want you to understand,” he said, threateningly, “that you must keep silence on this matter. If any hint of it gets about, it will be a very serious thing for you. I take it you don’t want to be mixed up in a murder trial. Very well, then; keep your mouth shut.”

Mrs. Billing was terrified and eagerly promised discretion. French questioned her further, but without result. She did not believe her late lodger was on bad terms with anyone, nor did she know if he had a birthmark on his upper arm.

French’s delight at his discovery was unbounded. The identification of the dead man represented the greatest step towards the completion of his case that he had yet made. He chuckled to himself in pure joy.

But his brain reeled when he thought of his four test points. If this news were true, he had made some pretty bad mistakes! Each one of his four conclusions must be false. As he remembered the facts on which they were based, he had to admit himself completely baffled.