Margaret Thatcher (1925 2013) was the dominant British political leader of our age. No postwar prime minister has equalled the impact she made on modern British history, nor matched her influence on the European and world stages. But, as she becomes a historical figure, how to distinguish myth from reality? The daunting quantity (and variable quality) of literature already available on Thatcher makes it decidedly difficult to discriminate the significant from the tendentious, superficial, and otiose. Moreover, because no comparable British politician has had such profound effects on...