Eileen broke in with a trace of excitement in her voice.
“Now I do see. You wanted to test which hand I used when I opened the cabinet. Both Douglas and I are right-handed. The thief was left-handed because he opened the other door—not the one we opened. Is that it?”
“That’s it,” admitted Westenhanger. “I told you it was obvious. And of course all that by-play was just meant to keep your mind off the crucial action, so that you’d do it perfectly naturally, without giving it a thought. See it, Douglas? Don’t forget the pattern on the back of the door; it’s most important, you know!”
“You had me there, I’ll admit,” confessed Douglas. “You wandered me completely, so that I hadn’t a notion what you were after. And so the thief’s left-handed, is he?”
“Looks like it, doesn’t it?”
Eileen stepped over to the cabinet and examined it for a moment or two.
“How, exactly, did you come to think of it, Mr. Westenhanger? I suppose it was the left-hand door that gave you the key?”
“There’s some confirmatory evidence,” Westenhanger explained. “Will you stand in front of the case, Miss Cressage? Now notice that you’ve the choice between the two doors if you wanted to get at the Talisman. You’re right-handed, so you choose the right-hand door, naturally. Besides, it’s always easier to turn a handle clockwise than counter-clockwise; and that favours the right-hand again, subconsciously. To open the cabinet you turn the right-hand handle as you turn a corkscrew, which is easier than turning the left-hand handle counter-clockwise.”
Eileen put out both hands and imitated the motion of opening the doors.
“That’s true enough,” she said. “I remember that sometimes a door handle gives one trouble if it works in the opposite direction from the usual way.”