“For several reasons that letter interested me. In the first place, it was addressed by somebody who was writing with his left hand; it isn’t difficult to see when that’s happened. In the second place, although the name was written in full, ‘Mr. H. Anderton,’ the address wasn’t in full; it was simply ‘The Inn, White Bracton.’ In the third place, the letter had been there a week, to judge by the postmark, and nobody had claimed it.
“Those derelict letters always interest me; it comes, I suppose, Bredon, of being a professional spy. And this one, lying about in a place which I’d gone to on purpose in the hope of picking up information, intrigued me particularly. The postmark said ‘Oxford,’ but there was nothing enlightening in that. I dallied with the temptation for a moment, then slipped the letter into my pocket, and left the White Hart without asking any questions at all. When I was round the corner, I opened the letter, and found that it was exactly the thing I had come for. It was from somebody who signed himself Nigel to somebody whom he addressed as Derek; and it explained in words of one syllable the whole system of the Bradshaw cipher which you solved this morning.”
“Have you got the letter here?” asked Bredon. “I’d rather like to see the postmark. Yes, the postmark’s all right; it was posted late on the day of Derek’s disappearance. And the envelope was untouched, I suppose, when you found it? But of course, you’d have been bound to notice if it had been tampered with. Yes, that letter’s genuine enough, and, as Mr. Quirk says, it’s all very interesting. I suppose you’ve got specimens of Nigel Burtell’s handwriting to compare it with?”
“Trust me for that. The whole thing’s genuine. And it looks rather as if we’d got to revise our whole view of the business, don’t it?”
“As how?”
“Why, on the face of it it looks as if the two cousins were both alive, and in active correspondence with one another. And if that’s so, all the other clues we’ve been following up, the photographs, and the two sovereign-purses, and you-know-what on the island, must all have been simply a blind of some sort. And the hole in the canoe must be either a blind or an accident. And I don’t quite see that we want to find the man in the punt any more. We certainly don’t want to drag the river above Shipcote.”
“Yes, but you’re going much too fast. You say, on the face of it both cousins are alive. But is that a necessary conclusion?”
“No, not necessary, of course. But it proves, surely, that one or other of them’s alive? It’s not very likely that a third person would be in the secret of the cipher.”
“Yes, I think it’s reasonable to assume that at least one of them is alive. But then, you go on to say that they’re in active correspondence. There I don’t agree with you at all; it seems to me much the most interesting feature of the case that the correspondence between them is so extraordinarily passive.”
“How passive?”
“Why, my dear chump, don’t you see that neither of them knows where the other is, or what’s happening to him? A week ago, Nigel wrote a very intimate letter to his cousin, addressing it to the inn at White Bracton. He had reason to believe that his cousin was at White Bracton; that means there had been some prearrangement; he did not know the name of the pub at White Bracton, therefore the prearrangement, such as it was, was very incomplete. Nigel sent a code, to be used in case of emergency—why hadn’t that code been arranged already? It means, surely, that when Nigel wrote there was already some hitch in the plan; things weren’t quite working out to time, and therefore it would be prudent to have a cipher.”
“Yes, I suppose that’s sound, as far as it goes.”
“But it’s not nearly all. The alias, H. Anderton, must obviously have been arranged beforehand. If Derek ever went to the pub at White Bracton—that’s to say, if he ever went to the right pub—he must have looked about for letters addressed to H. Anderton. And if he had found one, he would have lost no time in taking it down from the rack. You wouldn’t want to take any risks in such a correspondence.”
“Yes, confound it all, I wondered why the letter was unclaimed, but I didn’t see how important it was. You mean Nigel doesn’t know where Derek is?”
“Didn’t know, anyhow. And, what’s still odder, he thought he did know. Surely it’s fair to say that there must have been a disarrangement of their plans? And, if so, the clues we picked up round the island and so on may still have a meaning.”
“But this morning’s message looks as if they’d got in touch again.”
“Not a bit of it. If it was really Derek who wrote that post card, it shows that he hasn’t kept informed of his cousin’s movements in the least. If he had, he would have known, in the first place, that Nigel has gone down from Oxford; and in the second place he would know that Nigel’s movements have been suspicious, and that his old digs would be watched by the police. Therefore he wouldn’t have sent him an incriminating message at that address. (I say incriminating, because there is always a chance of any cipher being read.) No, if Derek wrote that post card, it was a hopeless shot in the dark. But, of course, Derek didn’t write that post card.”
“You mean that he can’t know the cipher, because he never got the letter addressed to him at White Bracton? But that letter may have been verbally confirmed since.”
“Not a bit of it. The two cousins haven’t met, or Derek would know that Nigel isn’t in Oxford any longer.”
“That’s true. But he might
