Reader, Lindsay Duncan.

And what's going past is the life of Guy Stockdale, a 62-year-old judge, who has been married forever, has two sons--Simon and Alan--and three grandchildren. For the past seven years, he's also had a mistress. Merrion Palmer is intelligent, attractive, and half Guy's age, which also makes her younger than both Simon and Alan. Her dad died when she was a toddler and she's well aware that Guy is something of a father substitute. For years the role of mistress has suited her, but, suddenly, this style of relationship isn't enough for either of them. They've both had enough of sneaking around and avoiding people, so Guy has momentously made up his mind to leave his wife, Laura, and marry Merrion. Marrying the Mistress dives into the shock waves that buffet the Stockdale family after Guy leaves Laura. The novel addresses the question of how his sons are going to cope, the explosive opinions of his forthright daughter-in-law Carrie and what his teenage grandchildren make of it all. Can any of them avoid taking sides? Should they? And what about the abandoned wife, Laura, a woman apparently so long-sufferingly self-sacrificing she makes Mother Teresa look selfish?