“It seemed to be one of life’s wonders,” observes Sherwyn Sexton, the not wholly unlikable cad at the center of Fay Weldon’s lively if sometimes frustrating new novel, “Before the War,” “that nothing happens and nothing happens and all of a sudden everything happens.” The line is a sly wink in a novel full of playful authorial interjections, in this case channeling an aphorism widely attributed to Weldon herself.

Eventfulness is indeed what fuels this comedy of aristocratic manners, set in a bygone era when Britain is in a state of collective shell shock and relative deprivation. “We like to dream the costume drama of Edwardian times, all fine clothes, glittering jewels and clean sexy profiles,” Weldon writes, “but we are less drawn to the 20 years between the wars.”