Two books in one:

The Education of Lady Frances
Lord Julian Mainwaring, Marquess of Camberly, was the very opposite of Lady Frances Cresswell's ideal. Mainwaring was the dazzling star of a London society that Frances scorned. He treated females as sensual playthings, while Frances believed women should be informed and independent.

Frances had no wish to have anything to do with this arrogant lord. But when he ordered his niece and Frances's friend, Kitty, to London for the Season, Frances had to come along to protect the young innocent from his influence. There was no one, though, to protect Frances, as she learned how strong love's power was, and how frail her defenses

Miss Cresswell's London Triumph
Cassandra Cresswell came by her learning naturally, having parents who were scholars. And being a London bluestocking never bothered her, until she discovered something special about an old childhood friend. Ned Mainwaring, however, was under the spell of Miss Arabella Taylor, as were most of London's bachelors. So Cassie would have to learn something new to outwit the little enchantress.