I actually have a book on this subject, I'll come back when I find it...that's on the tail of the Victorian Era.
Edit: it seems My lady would also be appropriate.
If she is being addressed by a man, you'll want him to mind his P's and Q's sharply.
if he is offering a kind, gentlemanly service such as assistance crossing the street, or into her carriage, or to hold a door, he might speak a little more.
he would be wary of how he should make the introduction, if he chooses to risk one.
"Christian names" AKA first names...are only used in the family circle, not by people not married or related to the woman.
She would never say "Call me Edith" for example.
Also I suggest ordering this book since it's the meat and tatos of the rules that govern polite society in that era:
I have it and others in my collection, but this is an excellent quick-reference.
http://www.google.com/products/cata...a=X&ei=tMZBTtHxOOu20AGEls3ACQ&ved=0CFEQ8wIwAA