Pining for Lord Lockhart by Jen Geigle Johnson

Charity watches each of her sisters make plans to marry, one by one, and she is overjoyed for their happiness, but she doubts she will ever feel much of the same. She is busy in her causes, in her book groups, in her thinking bluestocking ways, but she has a secret. And no one knows, not even the man himself. But through all of her forward thinking ways, she is pining for Lord Lockhart.

Lord Lockhart is the wealthiest man of any of their acquaintance. He recently received yet another inheritance when an old eccentric uncle passed on and he seeks for ways to use his money responsibly. Charity is a good resource for him in this regard. And he just might have secrets of his own where she is concerned.