There’s something reassuring about 98-year-old Diana Athill. She’s stately and well-ordered, like the gardens at Ditchingham Hall in Norfolk, her grandparents’ Georgian house where she spent long periods of her childhood. Yes, she really is of that class, though she doesn’t trumpet it (she was presented at court in the brief reign of King Edward VIII) and, as is well known, she is of more than a certain age — born in 1917, towards the end of the first world war but, in social terms, a throwback to the Edwardian era, and half a decade before the publication of Ulysses...