“A good many hundred, probably. As each division comes in and gets leave they all run to get their pictures taken, don’t they? And they want them by a certain time? Why? Because they’re going to sail, of course.”

“There’s no argument on my part.”

“But suppose that man’s name isn’t Booth? Suppose I told you he’d once been the court photographer at Vienna?”

Sergeant Gray whistled.

“Are you telling me that?”

“I am. My dressmaker is in the same building. She told me. He showed her a lot of photographs of the royal family.”

Every boy has longed at some period of his life to be a detective. Sergeant Gray suddenly felt the fine frenzy of the sleuth. But there was disappointment too.

“So that’s why you picked me up last night?”

“Not at all. But it’s why I came for you this morning.”

“Would you mind explaining that?”