Sir Herbert Butterfield, Master of Peterhouse, Cambridge (1955–68), Regius Professor of History (1963–68), and author of The Whig Interpretation of History (1931), was one of the leading historians of the twentieth century. A diplomatic historian and student of modern historiography, Butterfield was deeply concerned too with contemporary international relations, wrote much on the subject and, in 1958, created the ‘British Committee on the Theory of International Politics’. Drawing upon published and unpublished material, this article seeks to sketch an outline of Butterfield's career and thought, to examine his approach to international relations, and to reconsider his reputation in the field.