“Not since the Jermyn Street affair,” answered Mr. Elphinstone.  “We traced him in the medical register all right up to that point.  His name is Francis Meekin—­he’s various medical letters to it.  He was in one of the London hospitals with Gilbert Carstairs—­he shared those rooms in Jermyn Street with Gilbert Carstairs.  We found—­easily—­a man who’d been their valet, and who remembered their setting off on the hunting expedition.  They never came back—­to Jermyn Street, anyway.  Nothing was ever heard or seen of them in their old haunts about that quarter from that time.  And when we’d found all that out, we came straight down, last evening, to the police—­and that’s all, Mr. Lindsey.  And, of course, the thing is plain to me—­Gilbert probably died while in this man’s company; this man possessed himself of his letters and papers and so on; and in time, hearing how things were, and when the chance came, he presented himself to the family solicitors as Gilbert Carstairs.  Could anything be plainer?”

“Nothing!” exclaimed Mr. Lindsey.  “It’s a sure case—­and simple when you see it in the light of your knowledge; a case of common personation.  But I’m wondering what the connection between the Gilverthwaite and Phillips affair and this Meekin has been—­if we could get at it?”

“Shall I give you my theory?” suggested Mr. Elphinstone.  “Of course, I’ve read all there’s been in the newspapers, and Murray told me a lot last night before we came to you, and you mentioned Mr. Ridley’s discovery,—­well, then, I’ve no doubt whatever that this young gentleman is Michael Carstairs’ son, and therefore the real owner of the title and estates!  And I’ll tell you how I explain the whole thing.  Michael Carstairs, as I remember him—­and I saw plenty of him as a lad and a young man—­was what you’d call violently radical in his ideas.  He was a queer, eccentric, dour chap in some ways—­kindly enough in others.  He’d a most extraordinary objection to titles, for one thing; another, he thought that, given a chance, every man ought to make himself.  Now, my opinion is that when he secretly married a girl who was much below him in station, he went off to America, intending to put his principles in practice.  He evidently wanted his son to owe nothing to his birth; and though he certainly made ample and generous provision for him, and gave him a fine start, he wanted him to make his own life and fortune.  That accounts for Mr. Gavin Smeaton’s bringing-up.  But now as regards the secret.  Michael Carstairs was evidently a rolling stone who came up against some queer characters—­Gilverthwaite was one, Phillips—­whoever he may have been—­another.  It’s very evident, from what I’ve heard from you, that the three men were associates at one time.  And it may be—­it’s probably the case—­that in some moment of confidence, Michael let out his secret to these two, and that when he was dead they decided to make more inquiries into it—­possibly to blackmail the man who