This article presents the first addition in recent years to the canon of the British eighteenth-century statesman and political thinker Lord Bolingbroke (1678-1751), a manuscript essay 'On the Character of a Great Patriot'. For the first time, this article identifies Bolingbroke as the likely author of this unascribed, undated, and untitled essay in the Senate House Library manuscript collection. Using internal and contextual evidence, the article demonstrates that the 'Character' is a description of Bolingbroke's opposition colleague William Pulteney, and that it was written in the final months of 1731, mostly likely for publication in the opposition journal the Craftsman. The 'Character' dates from a period in which Bolingbroke wrote very little, and it is thus a crucial addition to his biography as well as an early exposition of his theory of opposition politics. Moreover, study of the essay shows that Bolingbroke drew extensively on the example of Pultneye when formulating his idea about the necessity of a systematic opposition party, not fully formulated until On the Spirit of Patriotism (1736). The 'Character' thus sheds further light on the important relationship between political practice and theory in the age of Walpole.