It was not until nearly eleven that Mr. Copperdock’s party broke up. Inspector Whyland’s deputy, strolling past on the other side of the road, noticed the parting on the doorstep, and observed that after the departure of his friends, Mr. Copperdock shut the door of his shop. A few minutes later he saw a light switched on in one of the front rooms upstairs. This he knew, from his experience of previous nights, was the signal that Mr. Copperdock was going to bed.