When waging war against the French in the late 1550s, Mary Tudor's deployment of extensive extra-legal powers to raise forced loans, revise the Book of Rates and employ martial law encountered public objection from neither Catholics nor Protestants. Charles i's resort to similar expedients when waging war against the French in the late 1620s provoked widespread hostile reaction. As Cromartie observes, ‘[w]hat had changed was not the government's behaviour, but the political culture in which it operated’ (p. 324). Investigating afresh why such a ‘precociously unified national culture’ (p. 1) as England descended into civil war in 1642, Cromartie's route lies via early modern legal history and, particularly, the effects of law on contemporary religious sensibilities. At the heart of this account is the role of extra-legal discretion, especially equity jurisdiction, which assumed increasing importance as personal monarchy yielded to rule-bound monarchy in the era of Fortescue and St Germain. Post-Reformation fluctuations between ‘Catholic’ tendencies to non-parliamentary governance and ‘Protestant’ preferences for law-bound government reflected innate continental Protestant insecurities and ‘owed almost nothing to Protestantism among common lawyers’ (p. 80). Indeed, the Elizabethan establishment's eschewal of a Presbyterian high Calvinism that potentially threatened English institutions only generated endemic theological, doctrinal and political anomalies that ‘made lasting consensus unsustainable’ (p. 119). More specifically, Cromartie identifies James vi & i's accession to power in 1603 as the moment when consent-based law was no longer ‘still politically innocent’ (p. 146), more due to ‘the hopes stimulated by his personal religion’ (p. 147), than generalised suppositions regarding Stuart absolutism. Thereafter, Cromartie's focus shifts somewhat from textual exegesis to reappraising ecclesiastical and political events under both James and Charles i to show that when ‘a humble land law system came to provide the language of political debate’ (p. 230), adversarial and litigious resonances resulted. Royalists who regarded the common law as an unvarying set of determinate rules instinctively distinguished between legal and non-legal argumentation, whereas parliamentarians instinctively championed its omnicompetence and centrality to the national experience. Claiming that ‘[t]he main conclusion to be drawn from this admittedly quite tangled story has to do with the sheer power of legal values’ (p. 261), Cromartie's constitutionalist revolution occurred when English common law was identified as the criterion of authority by the Long Parliament in 1641. His book concludes, somewhat abruptly, with an epilogue which connects this achievement with the ‘philosophical account of constitutionalist expectations’ (p. 279) subsequently supplied in John Locke's Two treatises of government (1689), drawing attention to Locke's reliance on key private law concepts of adjudication and trust in formulating his natural jurisprudence. The subtitle, The constitutionalist revolution, is well-chosen; it is, primarily, an eclectic essay on the history of English thought and, as such, self-consciously echoes John Pocock's The ancient constitution and the feudal law (first edition, 1957), though Cromartie explicitly inverts the Pocockian interpretation of common law as, first, custom and, secondarily, reason. Cromartie's book demands of its readership considerable prior historical and historiographical knowledge, but its success in probing recurrent interactions between early modern legal reasoning and religious sensibilities is both original and rewarding.