Not Quite a Lady (2007) is the final book in Loretta Chase's series about the Carsington brothers, but it's the heroine rather than the hero who makes this story stand out. As a teenager, Lady Charlotte Hayward bore a child out of wedlock after being taken advantage of by a seducer. With the help of her stepmother and a loyal maid, she hid the pregnancy from everyone else, including her father, bore the child in secret, and had him adopted. Since then she has been adroitly avoiding marriage, no mean trick for an attractive, wealthy, and well-born young woman, because in so intimate a relationship her secrets would come out.
This is my second favorite of the Carsington books after the incomparable Mr. Impossible. I thought what happened to Charlotte's son was a bit too good to be true given the strictures of the times, but this is an engaging, fun read.