“It is very good of you,” said Thorndyke, “and I need not say that the information is of great value, coming from such a highly expert source. As a matter of fact, your hint will be of great value to me.”

He shook hands with Mr. Britton, and, as the latter disappeared down the stairs, he turned into the sitting-room and remarked:

“There is a very weighty and significant observation, Jervis. I advise you to consider it attentively in all its bearings.”

“You mean the fact that these signatures are undoubtedly genuine?”