Was King Henry viii a tyrant? To some, the very question might seem inappropriate: an invitation into a world of ethics that is best left to the philosopher or theologian; a temptation to judge the distant past by the standards of the present, and thus to fall into the sin of subjectivity. If the concept of tyranny has its place within the historian's lexicon, then (so the argument might go) it should be reserved for the study of either the ancient or the late modern world, where tyrants seem to abound. Earlier generations, however, had few such scruples. The image of Henry viii as tyrant was fixed by the Elizabethan religious exiles who set out the first Catholic history of the break from Rome, but it can also be found in more unexpected places. The generation of schoolchildren weaned on H. E. Marshall's Our island story learned that, though he gave the people their English Bible, Henry viii was bad and selfish and died a cruel tyrant.

Both Greg Walker's Writing under tyranny and George Bernard's The king's reformation look to the later years of Henry viii, where the evidence for his arraignment is most obviously sought. Walker's approach is literary, focusing on prominent poets (Sir Thomas Wyatt, the earl of Surrey) and on lesser-known servants in the royal household (John Heywood, William Thynne) who used their writing to negotiate their responses to an increasingly autocratic monarchy. Bernard's subject – Henry viii's role in the religious upheaval that bears his name – and the records of state from which he constructs his account, are more historically conventional. The two books exist in a close relationship. Bernard supervised Walker's early doctoral research; Walker called on the manuscript of King's reformation when preparing his own text. Both offer strong and distinctive interpretations of the reign. Walker's book stands out for its imaginative and dextrous use of sources, whereas Bernard's may be remembered more for the vehemence of its argument.

Greg Walker's Writing under tyranny gallops through the relatively sunny early reign to reach the great matter of Henry viii's divorce, when courtiers attuned to the classical Renaissance began to ponder the similarity between their sovereign and the emperors Nero and Domitian. Readers familiar with Thomas More's writings on tyranny, from his early epigrams to his final allegory of Henry as the ‘greate Turke’, may be surprised by their relative absence here. Walker knows about More, of course, and has chosen to bypass the mountain of scholarship devoted to him in order to reach figures who were equally significant within their own contexts. Principal among them is Sir Thomas Elyot. Walker's treatment of Elyot is virtually a biography within an already very full monograph; sheer length is one of the few criticisms that can be levelled at this book, although its subdivision makes it easy enough to use. For forty years, our portrait of Elyot has been that captured by Stanford Lehmberg, who interprets The book named the governor (1531) within a king-praising tradition, quickening King Henry's desire for supremacy over the Church. Walker's reading is subtler, more radical and ultimately more convincing. The governor emerges as a highly critical commentary on the events of the early Reformation: a definition of commonwealth as a mixed polity, rather than absolute monarchy; a ‘handbook of liberal kingship’, more specific than More's Utopia, and targeted squarely at Henry himself.

That Elyot went on to write seven further works, including a dictionary and a medical textbook, all aimed in a similar direction, implies that he had little definable impact on the political culture that he yearned to remodel. It is difficult to make a case that any of Walker's authors managed to deflect Henry viii's kingship from its absolutist trajectory. No one alluded to Surrey's (shockingly frank) verse when he was indicted for treason in 1546, probably because so few had read it. But Writing under tyranny is more than a study in failure. Greg Walker's autopsies of multiple texts and authors, many of them obscure until now, enable us to analyse Henry viii from the perspective of his own political nation. Look behind the platitudes and propaganda, argues Walker, and you can find governors like Elyot and Wyatt writing in innovative ways to diagnose the ills of the body politic. This is a truly important book, a major contribution to the study of the early Tudor regime, and a master-class in how to read literature as historical evidence.

In an essay published in 2002 George Bernard explored what he called the ‘totalitarian’ ambitions of Henry viii, and the climate of intimidation that deadened criticism of his rule. The king's reformation picks up the theme, presenting six hundred pages of evidence, and another hundred of footnotes, that Henry was ruthless in character, convinced of his own rectitude, and ‘a king who in the 1530s turned into a tyrant’. Yet Bernard also gives us a Henry who truly believed that he was God's lieutenant; not a Protestant, but a sincere reformer nevertheless, who pursued his purifying agenda – the royal supremacy, monastic dissolution, the forcible correction of dissent – with vigour and success. The Henrician Reformation, in short, belongs to Henry: not to Cromwell (Bernard thus taking on Geoffrey Elton), nor to Cranmer (ditto Diarmaid MacCulloch), nor to evangelicals at court and university (ditto Alec Ryrie), nor to Anne Boleyn (ditto Eric Ives). If that Reformation involved more destruction than rebuilding, then the blame must fall on Henry.

There is much to admire here. This is a book with a bold thesis, argued with unswerving conviction. It is rich in archival research, reaching behind the printed calendars and sometimes exposing the misreadings of others. Henry viii's religion is characterised with care: an idiosyncratic devotion to both the mass and the royal supremacy, anti-Luther but sympathetic to Erasmian reform. There is a valuable reconsideration of the Pilgrimage of Grace as a religious rebellion, sparked by the monasteries and sealing their fate. Cromwell and Cranmer are demoted from factional leaders to royal servants, concerned above all to maintain the peace. Bernard has the courage to give clear answers to big questions: where the Henrician Reformation came from, and why it was not more effectively opposed.

It would be good to know what Bernard makes of the 1540s, given the consistency that he sees in the royal will: the seven years following Cromwell's fall are despatched in sixteen pages. The real problem with this book, however, is its tone. Elton is ‘misleading’, John Guy is ‘mistaken’ and ‘fails fully to grasp’. Paragraph after paragraph is devoted to unpicking issues that others have misunderstood. Scores, old and new, are settled. Bernard commands high respect in Tudor studies; his opinions matter; it is strange, then, that he is so ungenerous. Were this an undergraduate dissertation, its thinking and conclusions would clearly be alpha, but its attitude to the historiography would leave examiners bemused.