In 1908 Ellen Wilkinson, a fiery adolescent from a working-class family in Manchester, was "the only girl who talks in school debates." By midcentury, Wilkinson had helped found Britain's Communist Party, earned a seat in Parliament, and become a renowned advocate for the poor and dispossessed at home and abroad. She was one of the first female delegates to the United Nations, and she played a central role in Britain's postwar Labour government. In Laura Beers's account of Wilkinson's remarkable life, we have a richly detailed portrait of a time when Left-leaning British men and women from...