“Perhaps you’d better,” said Thorndyke. “It may not be Mr. Britton, and I don’t want to be caught and delayed just now.”

However, it was Mr. Britton; a breezy alert-looking middle-aged man, who came in escorted by Polton and shook our hands cordially, having been previously warned of my presence. He carried a small but solid handbag, to which he clung tenaciously up to the very moment when its contents were required for use.

“So that is the camera,” said he, running an inquisitive eye over the instrument. “Very fine one, too; I am a bit of a photographer myself. What is that graduation on the sidebar?”