Graven With Diamonds, By Nicola Shulman

When I first began to read poetry seriously at school, "practical criticism" still held sway. This approach promoted the idea of an unmediated dialogue between the reader and the text – a sort of naked encounter session, free from the deceiving clothes of context. And it so happened that one of the poems stripped from its history that I enjoyed most delivered the electrifying delight of déshabillé. A masterpiece of petulant erotic longing (hence, perhaps, its allure for teenage readers), this lyric by Sir Thomas Wyatt begins "They flee from me that sometime did me seek". It goes on to recall a rejected lover's tryst with a fickle lady who "When her loose gown from her shoulders did fall/ And she caught me in her arms long and small/ Therewithal sweetly did me kiss,/ And softly said, 'Dear heart, how like you this?'"

Not only yearning youngsters will fall for Wyatt (1503-1542) in this mood. Many of his 170-odd authenticated poems (the attribution wars still rumble) dance us through the minefield – sexual, political and religious – of Henry VIII's court with an elusive melancholy charm that never drops the veil of mystery. Like the mocking minxes it evokes, who themselves slip between stock poetic silhouettes and warm-blooded womanhood, Wyatt's poetry teases, seduces, succumbs, changes its mind - and often flees. For a novice reader denied the right even to ask about the world of history and biography behind this soft-focus screen of desire and danger, the exposure proved frustrating on several levels.

Now Nicola Shulman has written the book that I craved then. Although modern editors aplenty have pored over Wyatt's work, she properly maintains that this scholarly searchlight tends to blind lay readers and obscure the verse, leaving "a legacy of under-appreciation". No longer: Graven with Diamonds is one of the most persuasive and pleasurable accounts of English Renaissance poetry to appear from a general publisher in years. Moreover, as a finely-shaded portrait of the writer as a man of power "whose whole creative life was spent in the intertidal strand where realpolitik and poetry mingle", it braids text and context into an enriching feedback loop that proves the sheer impracticality of "practical criticism".

Shulman's subtitle – "the many lives of Thomas Wyatt: courtier, poet, assassin, spy – misleadingly suggests a cloak-and-codpiece potboiler for fans of TV's The Tudors. Yet she chooses targets and themes with something of her subject's high-born hauteur. Shulman fixes a shrewd and illuminating gaze on the gnomic love lyrics that Wyatt wrote for narrow circulation at Henry's court in the 1520s and 1530s, a "closed, incestuous coterie" that would "rarely have exceeded 100 key courtiers". Wyatt's poems saw print only posthumously, in 1557. Subtle and ingenious, this study presents them as form of elite samizdat, or even as "the Facebook of the Tudor court"; close-packed bomblets of innuendo and insinuation designed for a febrile time and place when "poetry was the hot vehicle for gossip and rumour".

With unflagging flair, wit and tenacity, she follows the threads of romantic intrigue, factional conspiracy and theological dispute in Henry's households as he swapped wives, changed directions and broke with Rome. Rather grandly, Shulman mostly overlooks Wyatt's pastoral satires and Penitential Psalms. Then action-packed final chapters trace Wyatt's thrilling but hapless (a favourite word of his) missions as "an early-modern James Bond" to the French king Francis I and the emperor Charles V. English diplomacy strove to prevent the major powers of Europe from ganging up on the heretic-friendly wife-slaughterer over the Channel.

Was Wyatt a lover of Anne Boleyn, as long-standing legend has it? His imprisonment in the Tower in 1536, just as the Queen met her fate, hints as much. His first jail spell – the second came in 1541, when his patron Thomas Cromwell fell – certainly drew some great, anguished verse ("These bloody days have broken my heart./ My lust, my youth did them depart.") Shulman argues cogently that Wyatt betrayed the Boleyns, and was banged up so that he might rat at leisure on the clan. Hence the gnawing guilt.

As for their liaison, we still don't know everything. But her account fits in with the forensic acuity of this book as a whole. Steered by the conventions of courtly love, Wyatt's lyrics – and the sophisticated "pastime" they fed – both sanctioned and controlled adulterous desires. The rituals permitted the expression of a hands-off admiration for a married lady – but the licensed formula might itself prove a bluff that hid genuine passion. This courtly sport "was played at a high pitch of suggestiveness, balanced on a blade between earnest and game". To keep one's head (in every sense), ambiguous words had to slip and slide, revealing while concealing, forever on the move. The "single folded piece of paper" bearing a Wyatt verse that rippled through the court both told its truth and kept its counsel. As Shulman shows with quite spectacular intelligence, its meaning was "mutating with the mutability of the times".

Remarkably, Wyatt outlived both the failure of his Continental quest to liquidate the Papists' leader, Cardinal Pole, and the execution of Cromwell. It seems, argues Shulman, that the pretty, doomed Catherine Howard saved him before Henry's mad wrath axed her too. He died of a fever at Sherborne, not far from the home of his ever-patient mistress (and mother of his son), Besse Darrell. How well did the poetry endure? Very much the in-the-know châtelaine among plodding bourgeois critics, Shulman airily claims that the "private semaphore" of Wyatt's genius proved "incompatible with print culture". Up to a point, milady. This book gives it new life.