The woman beneath the bluestockings was. . . a bluestocking, but a warmer, more self-critical person than her public image as reformer with a ""governing class"" mentality, wife in ""a partnership"" with ""her boy"" Sidney, credulous booster of the Soviet Union in the '30's, would suggest. This biography, the first in more than two decades, draws heavily on her diaries. Half the book is devoted to the years before the 34-year-old heiress and ""social investigator"" picked Sidney from among the Fabian leadership. It is the more interesting and psychologically acute half: Mrs. Muggeridge, the daughter of one of Beatrice's eight sisters, succeeds in recreating the family ambiance, childhood agonies over religion and an unloving mother, her tutorship by Herbert Spencer, gradual preoccupation with poverty, and her romance with the dashing Joseph Chamberlain. Then it's the familiar story of writing and legislating, the London School of Economics and the Labour Party, collaborations and quarrels with prominent rebels like Shaw and Wells, and vicissitudes of popularity and morale. A lively, fair-minded, quick-reading study.