Barbara Pym: A Very Private Eye: An Autobiography in Diaries and Letters; Edited by Hazel Holt and Hilary Pym; E. P. Dutton; New York; $19.95. “Be more wicked, if necessary,” Barbara Pym’s agent once suggested as she revised her early novels and prepared to make her first wild dash through the gauntlet of London publishers. “Can you imagine an old spinster,”...