“Very soon, however, that theory was also bound to collapse.  Mr. Fairburn, whose reputation as an investigator of crime waxes in direct inverted ratio to his capacities, did hit upon the obvious course of interviewing the managers of the larger London and Liverpool agents de change.  He soon found that Prince Semionicz had converted a great deal of Russian and French money into English bank-notes since his arrival in this country.  More than L30,000 in good solid, honest money was traced to the pockets of the gentleman with the sixteen quarterings.  It seemed, therefore, more than improbable that a man who was obviously fairly wealthy would risk imprisonment and hard labour, if not worse, for the sake of increasing his fortune by L10,000.

“However, the theory of the Prince’s guilt has taken firm root in the dull minds of our police authorities.  They have had every information with regard to Prince Semionicz’s antecedents from Russia; his position, his wealth, have been placed above suspicion, and yet they suspect and go on suspecting him or his secretary.  They have communicated with the police of every European capital; and while they still hope to obtain sufficient evidence against those they suspect, they calmly allow the guilty to enjoy the fruit of his clever roguery.”

“The guilty?” said Polly.  “Who do you think—­”

“Who do I think knew at that moment that young Schwarz had money in his possession?” he said excitedly, wriggling in his chair like a Jack-in-the-box.  “Obviously some one was guilty of that theft who knew that Schwarz had gone to interview a rich Russian, and would in all probability return with a large sum of money in his possession?”

“Who, indeed, but the Prince and his secretary?” she argued.  “But just now you said—­”

“Just now I said that the police were determined to find the Prince and his secretary guilty; they did not look further than their own stumpy noses.  Messrs. Winslow and Vassall spent money with a free hand in those investigations.  Mr. Winslow, as the senior partner, stood to lose over L9000 by that robbery.  Now, with Mr. Vassall it was different.

“When I saw how the police went on blundering in this case I took the trouble to make certain inquiries, the whole thing interested me so much, and I learnt all that I wished to know.  I found out, namely, that Mr. Vassall was very much a junior partner in the firm, that he only drew ten per cent of the profits, having been promoted lately to a partnership from having been senior assistant.

“Now, the police did not take the trouble to find that out.”

“But you don’t mean that—­”

“I mean that in all cases where robbery affects more than one person the first thing to find out is whether it affects the second party equally with the first.  I proved that to you, didn’t I, over that robbery in Phillimore Terrace?  There, as here, one of the two parties stood to lose very little in comparison with the other—­”