The conduct of the British government's financial affairs during the Duke of Newcastle's tenure as First Lord of the Treasury has never to my knowledge been specifically investigated. This gap in our understanding of the eighteenth century is doubly puzzling: the period itself, during which Britain won a war and an empire, is pivotal in the kingdom's history; moreover, the sources for such a study are uncommonly rich for precisely those years in which the duke held the office. The lack of such an analysis, however, has not prevented several authorities from passing severe judgments on the duke's handling of financial affairs, and while these authorities speak from extensive knowledge of the Treasury and its complexities, I have come to conclude that their assessments are too harsh—a view I shall elaborate at the end of this essay. But even if the reader should conclude at that point that my flirtation with revisionism is itself ill-founded, there is yet another value in examining the Treasury under Newcastle: as in perhaps no other period we can sometimes see decisions at the Treasury actually being made, ideas being transmitted, and problems being analyzed. And above all we can see in some detail how Britain's remarkably successful governmental financial machine operated.