Ambler's account of Simon de Montfort is an interesting, well researched and (at times) very insightful look into the character of a hugely important figure in English history, but one which is marred by a somewhat rose-tinted and romanticised view of her central figure.
There's no doubt that Ambler knows her stuff - there's evidence of a lot of research into aspects of de Montfort's past and that of his family, and her writing about Simon's father, family identity and the forces which shaped his character are insightful, well considered and offers a very good understanding of much of his mindset. Ambler writes very well, with a generally brisk pace, an accessable approach, and a good eye for evocative tableau where appropriate, most notably whenshe moves beyond the shores of Albion and talks about their escapades on the continent and the Middle East. She deploys source material well without being excessive, deploying a nice balance of apposite quotes and well-chosen paraphrasing to keep the pace up.
Much of this good work, is, however, undone by her central argument, which is at best somewhat naive, and at worst deliberately blinkered for the sake of making a good narrative. As much as de Montfort had a huge influence on the rise of English rights (calling the first true parliament, limiting monarchy and extended key rights to those untouched by Magna Carta), Ambler seems to ascribe these moves towards a genuine altruism and revolutionary spirit in Simon, who she portrays as in almost hagiographical tones as above the factionalism, political nous and unpleasantness that she is more than willing to ascribe to his opponents.
In this line, Ambler glosses over some of the more obvious flaws of Simon's character (unbearable arrogance, a hot temper, casual cruelty, hypocrisy and a huge ego), ascribing them to family tradition, faith in Christ or stating that his friends loved him all the same for it. In the same vein, there seems to be no consideration of Simon's true motives when pushing through reform, assuming altrusim where the more likely culprit is cynical populism, pandering to disaffected parts of the population (such as Londoners) to build his power base and launch a coup to place him in de facto control over England. This results in a genuine surprise when Simon immediately breaks his own laws to enrich himself and settle old scores, or when his allies quickly realise that life was better under the previous regime and move against him.
All in all, there is some genuinely excellent historical work here, well written and presented in a manner which is accessable without being patronising or cliched. Unfortunately, the decision to start the narrative with Simon's heroic death in battle seems to reflect an approach which prioritises narrative over hard analysis, where facts are slotted in to support the romance of a last beacon of chivalry brought low by the forces of cynicism and tyranny rather than the reality of a more complex and flawed figure. Overall, it's not without value, but I would recommend reading with Marc Morris' 'A Great and Terrible King' to provide a counterpoint.