Once Bitten, Twice Shy — Christina Courtenay

Jason Warwycke, fourth Marquess of Wyckeham, is charged with introducing his nephew Robert into London society, with a view to finding him a suitable wife. At a ball, they make the acquaintance of the Templeton sisters, twins Serena and Ianthe. While his nephew is dazzled by the beautiful but scheming Serena, Jason is surprised to find himself attracted to the bookish Ianthe. Following his first wife's death, Jason was dubbed 'Lord Wicked' by the gossips, but despite this, he and Ianthe embark on a whirlwind romance, much to the dismay of his grasping relatives.