Hey, it isn't just us English Sarah/Agnes. How many perfect text-book speakers do you know in any language? (-:
Jane Austen's world was obviously far different from today in many ways and she used the language of the upper-middle class level rather than street speak of maket traders etc. Heretfordshire would also have local accents and England is renown for its variety of dialects. None of this is relevant in a conversation between Darcy and Elizabeth, but they didn't write the story, Jane Austen did and we have no real clue to how she herself spoke outside of the written word. The point I'm trying to make is that any of us can comply with formal literary rules when writing, but do we do that in normal conversation? There are several examples of words in J.A's stories that would not be spelled that way today but they have been left as long as they are understanable. Whilst every attempt at authenticity has tried to be complied with, most editions have been corrected grammar wise to some degree. My own current hardback version is the Penguin edition of 1995. It contains a copy of the original title page which, gramatically speaking, is a joke. My point is mistakes can occur amongst the best.