It occurred to me to wonder how much about the KKK was known in 1890s Britain, how much of it was fact, and how much of it was mythology- that last wouldn't surprise me at all, considering how much Conan Doyle mythologizes the United States in his stories (with probably the most obvious example being the Mormon plotline in A Study in Scarlet).

By inference, it would have been something that was NOT well known- as an American in the 21st century, I obviously found the mystery incredibly easy to solve with the two facts of "southern plantation owner" and "KKK," so if Conan Doyle was writing a story that he wanted to dazzle his 19th century British readers with, he probably wouldn't have picked something that everyone could have put together easily. In this case, did he pick something deliberately obscure, or something which was reflected in popular knowledge/culture in Britain at the time but was still not completely obvious? Would the fact that the KKK had dissolved in 1869 mean that it was obscure due to being an outdated reference? Was the KKK used as a device in other popular British literature at the time?

And, of course, secondary question- how accurate is the story, specifically as far as the orange pips? The implication in the story is that Holmes reads information about signs sent through orange seeds or sprigs of leaves out of "the American Encyclopedia"- but of course Conan Doyle could have been making this up/wrong about this as well. Did Conan Doyle (attempt to) base the story on facts, or start off with the KKK as a generic evil organization that he then changed to suit plot purposes?

Thank you!