I'm trying to locate a solid source that states that Cather preferred British spellings to American spellings, but so far have come a cropper. Online I found the Bernice Slote edition of Uncle Valentine and Other Stories, which states that “In ‘Coming, Eden Bower!’ Willa Cather for the first time used the English spelling in words like ‘neighbour’” (183), but felt this was inconclusive. I checked the textual essay in the Scholarly Edition of Youth and the Bright Medusa, which confirms the substitution of English spelling for American in this book (470, 478), but does not indicate that this was Cather’s personal preference; on the contrary, it may have been house style (470). I checked Woodress on the publication of YBM, and found lots of publishing details, but nothing about Cather's spelling preferences; I also checked the online Calendar of Letters to see if I could find anything, but had no luck; the same with re-reading some key letters in the print Cather Letters, though it may be there someplace.
If anyone has any suggestions, I would greatly appreciate it. Please feel free to tell me, too, if I'm fabricating the idea of "Cather preferred English spellings" because it fits an argument I'm making!
Thanks so much.