“Verdict, natural causes,” went on Mac, unperturbed. “He was supposed to have had some sort o’ heart failure, but there was, if I remember aright, some doot aboot the question.”

“Why,” asked Shelley, “what was the doubt?”

“Och, ’twas nothin’,” answered Mac. “’Twas only that he left a good deal o’ cash to a young schoolmaister in the country somewhere, and the young fella was in the Readin’ Room on the same day as the old chap died. And when that sort o’ thing happens, ye ken, there are aye folks unco’ ready to put twa and twa thegether, and mak’ ’em five.”

Shelley looked up in surprise. This was suggestive of a new line of investigation. It was new information with a vengeance. He felt that he knew the answer to his next question before he asked it—yet he was impelled to ask it, just the same.

“What was the name of the young schoolmaster? Does it happen to stick in that queer old head of yours, Mac?” he asked, with a grin.

“It does,” returned Mac, unabashed, for his phenomenal memory he regarded much as other people regard their hair or their teeth—as a fact of nature, to be accepted, but not necessarily to be in any way proud of. “The young fella’s name was Henry Baker. He was Wilkinson’s cousin.”

Once again, as so many times before in his career, Shelley was up against an acute problem. Many impetuous men would, on receipt of this information, have hurried off to arrest the young man at once, but Shelley realised that it was quite possible, in spite of the undoubtedly serious evidence against him, that he was innocent. In any case, he was probably quite safely stowed away at Pinner—and Cunningham would have some more facts and theories about him to be added to the rapidly growing accumulation.

“Thank you, Mac,” he said, not showing in his face the feeling of delight that was surging up within him. “That’s very useful. I hope it’ll lead to our getting our man once again.”

“Don’t thank me,” said Mac. “’Tis nothing, I assure ye. Nothing more than a little gift, that the government underpays me for using.” And he stalked out of the room, leaving Shelley with a smile still on his face, for Mac’s perpetual grumbles at the smallness of his salary (which was actually not so small, after all) were one of the standing jokes among the higher ranks at Scotland Yard.

Shelley drew a sheet of paper towards him, and, as was his wont when in the middle of a difficult case, wrote out a summary of what he had as yet discovered. Several people would have been surprised if they could have read what he wrote, for Shelley, as has already been noted, could on occasions appear disarmingly simple when, in reality, he was laying traps of the deepest guile.