The first volume of this double-decker epic, published in 2020 and running to 760 pages, left the hapless King Henry III wandering with Emsworthian insouciance into one of the greater constitutional crises of English history. Here, in volume two, the storm at last breaks. In 1258, the barons rebelled. The king became a mere cipher, approving a baronial programme of ‘reform’. Attempts to restore royal authority, beginning in 1259 with the negotiation of the Treaty of Paris, foundered upon the rock named Simon de Montfort. Simon refused to abandon either his personal grievances or the wider cause of ‘reform’. After several episodes of open warfare in 1263–4, the king was taken prisoner at the Battle of Lewes. In August 1265, the tables turned. Simon and many of his principal supporters were killed at the Battle of Evesham (at which the king only narrowly escaped death). Peace should have followed. Instead, thanks to the vengeful intransigence of the royalists, there were further years of chaos, including the assault on rebel Kenilworth, still the longest siege in English history. The king himself thereafter declined into sedentary futility, with the future Edward I, his son and successor, abandoning a still war-ravaged England for the glamour of crusade.

Told thus as a brief catalogue of events, there seems little to justify spinning this fourteen-year history out to 639 pages of text. Nor is there anything here fundamentally new. Writing in the two decades after 1925, E F Jacob, R F Treharne and Sir Maurice Powicke effectively mapped the contours of what is still generally considered a period of ‘baronial reform and rebellion’. Fine biographies of Simon de Montfort, by Charles Bémont (1884), Margaret Wade Labarge (1962), John Maddicott (1994) and Sophie Ambler (2019), have exposed the chief rebel’s galvanic combination of fanaticism and self-interest. Maddicott’s The Origins of the English Parliament (2010) deals forensically with the chief constitutional innovation of this period: Simon’s manipulation of the greater conciliar meetings of laity and clergy to include, from 1265, representatives not only from the shires but also from the chief English boroughs.

Writers from Raphael Holinshed to David Hume and William Stubbs long ago acknowledged the period’s significance for the emergence not only of Parliament but also of the practice of seeking parliamentary assent for taxation and royal statute. If Magna Carta remains the foundation stone of English liberty under