Few themes highlight the ambiguities of eighteenth-century parliamentary sovereignty better than foreign policy. The monarchy retained almost unfettered power over diplomacy, only needing to consult Parliament in cases that required expenditure. But the monarchy hired foreign auxiliaries so often during the eighteenth century that few treaties were immune to parliamentary scrutiny. Cultivating goodwill between subsidies, the government would sometimes lay diplomatic correspondence unrelated to finance before Parliament. Thus Parliament parlayed its power of the purse into a partial oversight of international relations.

Parliament's role in foreign policy has been the subject of occasional articles by Graham Gibbs and Jeremy Black, but now Black has published a book-length treatment of the subject. Parliament and Foreign Policy in the Eighteenth Century will be the essential reference for anyone interested in Parliament's engagement with foreign affairs.

Its primary achievement is empirical. Black demonstrates an exhaustive acquaintance with British sources, published or not. But his real contribution is the application of foreign manuscripts to parliamentary history. These are particularly valuable, in that they show how domestic opposition gave hope to Britain's enemies and pause to its friends. Of course, Britain was not alone in this respect. Indeed, British diplomats complained that representative assemblies made Sweden and the United Provinces unreliable allies. Black's use of foreign sources and his comparative perspective are welcome antidotes to the exceptionalism of much parliamentary history.

Black supplies chronological as well as geographical context. Contrary to the expectation that Parliament's diplomatic competence would have increased over the course of the eighteenth century, Black proves that in fact the opposite was true. Wanting to distinguish himself from his German-born predecessors, George III avoided using British resources to defend his Hanoverian electorate. He concluded correspondingly fewer of the subsidy treaties that invited parliamentary attention. Black's narrative is appealingly counterintuitive but begs the question of when the monarchy lost its diplomatic prerogatives. He might have extended his analysis beyond 1800, especially as he treats the seventeenth-century origins of Parliament's role in foreign policy.

Interpretively, Black is at his best when doubting the existence of a single national interest. Having first done this in European International Relations, 1648–1815 (2002), he now applies the model to Britain. Black blames Whig history for the tendency to identify a singular reason of state, although his citations come more precisely from the discipline of diplomatic history. But he is right to rescue backbenchers from the condescension of posterity. The country squires may have been parochial, but their local roots gave them a better sense of a robust foreign policy's social costs. In his appreciation of subjectivity, Black is postmodern malgré lui.

While he focuses on foreign policy, Black necessarily addresses methodological issues common to all parliamentary history. In a chapter assessing the acuity of speakers’ contributions concerning international affairs, he also considers their oratory more generally. This might have been stronger if he had situated parliamentary debate in the larger context of public speech, as Joe Meisel has done for a later period. Black could also have profited from cultural historians’ work on performance and ritual. Another of his chapters traces the improvement in parliamentary reporting over the course of the eighteenth century. But Black's optimism about the accuracy of late-eighteenth-century sources would be more persuasive if he had addressed Dror Wahrman's doubts about their objectivity.

When Black does address the broader historiography, it is usually to protect Parliament's autonomy as a field of inquiry. His bête noire is John Brewer, who emphasized Parliament's cooperation with the executive in Sinews of Power (1988) and its sensitivity to public opinion in Party Ideology and Popular Politics at the Accession of George III (1976). Black's contrast between high politics and the public sphere is strange, coming as it is from an historian who has devoted much of his career to chronicling the growth of the British press. It also conflicts with many of his sources, which illustrate Parliament's dependence upon newspapers for both information and publicity. Black runs the risk that, in upholding Parliament's distinctiveness, he simultaneously reduces its relevance.