He tells me that while he was going around the house this afternoon he found the outside door of the back staircase unlocked." "Do you mean the door at the bottom of the staircase in the left wing ?" asked Caldew.
"Precisely." "I understood from Miss Heredith that this door was always kept locked." "So it is, as a rule.

It was only by chance that the butler discovered this evening that it had been unlocked.

You had better explain to the detective, Tufnell, how you came to find it unfastened." "I was going round by the back of the house this evening," said the butler, coming forward.

"As I passed the door I tried the handle.

To my surprise it yielded.