The Many Sins of Lord Cameron by Jennifer Ashley 

Cameron Mackenzie is a man who loves only horses and women—in that order—or so his mistresses say. Ainsley Douglas is a woman with a strong sense of justice and the desire to help others—even if that means sneaking around a rakish man’s bedchamber.

Which is exactly where Cam finds her—six years after he caught her the first time. Only then, she convinced Cam she was seeking a liaison, but couldn’t go through with it because of her husband. Now a widow, she’s on a mission to retrieve letters that could prove embarrassing to the queen. Cam has no interest in Ainsley’s subterfuge… Read more.