Helen Simpson is not a prolific writer; six slim collections of short stories in 25 years, each timed quinquennially with what seems, at least retrospectively, like impeccable forward planning. In fact, time, we shall see, is what her career so far has been about. She has also heroically resisted the pressure —and there must have been a significant one, at least towards the beginning — to move on from the short form and deliver a novel, as if the short story were not an entirely different genre but just a warming-up exercise before the heavyweight training session of the novel.

Cockfosters...