This is either to Caroline or to Ruth B, or to anyone else: what is the basis for the assertion made in Ruth's post about "lawyer" usually being employed for barrister? That makes sense to me; however, when I looked up lawyer in the OED after my last post, it said that the term could mean anyone in the law but that it was often used in a colloquial sense to refer to attorneys or solicitors. If that's true it might mean that John Knightley is in fact an attorney, though obviously one of high status. It would be good to know.
Also, Caroline, I don't know how much more research you wish to do, and how much access you have to a good library, but the book where I got the information on attorneys, etc. was by W.J. Reader, "Professional Men in the 19th Century" (or something similar). It might discuss specific uses of terms, and would probably be less trouble to use than searching web sites.