The problem of existing copies

That a book exists is not, you might think, a problem.  When I was working at the British Library a couple of years ago, the more usual difficulty was that a book no longer existed, generally thanks to somebody dropping a bomb on it during the Blitz.  (Potential future article: "disappeared religious fiction.") Last night, I was idly leafing through my copy of Sarah Maria Fry's The Little Watercress Sellers, first published in London by the Religious Tract Society in 1854 and then reprinted the following decade by the American Sunday-School Union (among others), and noticed the following advisory on the copyright page: "The following story is reprinted, with large omissions and changes of phraseology, from the London Religious Tract Society's press."  Ah, I thought--I'd best go look at the original.  Some quick searching turned up, not the book, but a footnote by Carolyn Steedman noting that there weren't any originals.  Double-checking revealed that the last-known copy had been held by the British Library, and...yup, there was the "D" prefix. 

From a literary historian's POV, this raises certain awkward questions.  Because, on the one hand, you do indeed have something related to the original--but, on the other hand, the alterations are a) silent and b) made without the author's consent.  What "large omissions"? In cases where I have been able to compare the American and English versions, the American publishers have done everything from changing the work's denominational affiliation to cutting out local cultural references deemed too obscure for American kids; here, I suspect that something sneaky has gone on with the little watercress sellers' mysteriously appearing and disappearing mother.  No way to check, though.  It's not clear to me that you can really use the resulting text in a discussion of nineteenth-century religious fiction in Britain, for the very simple reason that there's no way to figure out what a British reader would actually have encountered.  Or, at least, the only way to use it would be for purposes of brief plot summary.  But you could certainly study The Little Watercress Sellers as it survives in the context of nineteenth-century religious fiction in the United States.