He was not disappointed. It came out, in the course of a conversation between him and Houlder, the builder. It seemed that Houlder, who was an occasional frequenter of the Cambridge Arms, had mentioned, early in the month, that a new tenant had taken Number 407, and that he had got the job of altering the premises for him. Mr. Copperdock had displayed great interest in this remark, and as a result Houlder had invited him to come and look over the place. Mr. Copperdock had accepted, and he and Houlder had been over every inch of it. This might have been pure curiosity on Mr. Copperdock’s part, but at least the fact was significant. Inspector Whyland stored it in the mental pigeonhole which already contained the note that Martin and Copperdock had done considerable business together in the past.