Oh, dear. I'm digging myself in deeper and deeper here.
Well, I'm a woman--not sure about always being a "lady,"
but in your usage, yes, I'm a lady. "Del" is short for "Delphine," and I live in a town named Mobile.
"when one moves in the polo-playing set"---Okay. "One" as a pronoun is considered to be a little pretentious
in AE, though not in BE. As this link says, the more you use it, the more pretentious it sounds, which is why I used it as often as possible in my little funny aside to Amigos4. Polo is a sport associated with the very wealthy (it's expensive...all those horses. Ralph Lauren chose the name for his clothing line for just that association). A "set" is a term for a group of people linked by a common interest ("the jet set"). And to "move in" a set, or a "circle," is a rather grand way to say "associate."
Don't you know Millicent VandeRich? The last time we took the jet to Monte Carlo for the weekend, we had dinner with her. Such a delightful woman.
So sorry. I'm afraid I don't move in