Joanna Trollope has written a series of novels exploring the effects of unexpected crisis on middle-class lives. A clergyman’s wife braves her husband’s anger to stack shelves in the local supermarket. A happily married woman takes a lesbian lover. A farmer commits suicide after his brother’s wife dies of cancer. Each of these events acts as a catalyst for change, but, as when casting a stone into a pool of water, it is impossible to predict quite how far the ripples will spread.

In Marrying the Mistress, the chain of cause and effect apparently begins when a judge abandons his wife after forty years in order to marry a young woman half his age. This is not, however, a sudden decision. Guy Stockdale has been seeing Merrion Palmer for seven years, although their