The public can learn more about Holbein's important place in art history at two recently opened exhibitions. Holbein and the Renaissance in the North at Frankfurt's Städel Museum explores Holbein's work – and that of his father, Holbein The Elder – in the context of the Northern Renaissance; while in London’s Buckingham Palace, works from the Royal Collection are on show as part of Holbein at the Tudor Court. This exhibition of more than 100 artifacts, including paintings and miniatures, is centred around 40 portrait sketches – some paired with the completed painting – made during Holbein’s time in England and rarely exhibited due to their fragile nature.

The experience of being up close to these historic characters is "incredible", says Dr Kate Heard, curator of the Royal Collection's exhibition and author of the accompanying book, Holbein at the Tudor Court. "You see faces that are known only through Holbein's portraits − these amazing figures who we read so much about."

But we also learn about Holbein himself and his perfectionism, evident in the painstaking reworking of a jawline or the profile of a nose. "His character and his concerns come out through the drawings as much as his sitters… You really get the sense of looking over his shoulder and seeing him at work," Heard tells BBC Culture. "You see him recording texture and colour by smudging chalk or sharp lines; or recording in words: 'velvet', 'satin', 'damask'; or 'it's black', 'it's purple', 'it's red'."

The exceptional access required for these intimate sittings saw Holbein admitted to Anne Boleyn's private rooms in the early 1530s, where he sketched her in a satin bedgown, thought to be a gift from the king. Like so many of Holbein's sitters, she would be executed during Henry's tempestuous sovereignty, but Holbein had no shortage of patrons and, with Anne gone, his career reached new heights when Henry put him on the royal pay roll and instructed him to paint a mural for his Privy Chamber in Whitehall Palace.

"The extraordinary thing about his position... was his proximity to the inner workings of the court," Franny Moyle, author of The King's Painter – The Life and Times of Hans Holbein (2021), tells BBC Culture, describing the closeness to the King as "a measure of your importance".

But such access was not without risk. Holbein arrived in England as the first of many court dramas was unfolding. The King's forbidden love for Anne Boleyn, and Rome's opposition to a divorce from Katherine of Aragon, was about to trigger a radical shift in the power dynamic between monarch and Church, and catapult the country into the Reformation. Those whose opinions were at odds with the King's risked being tried for treason. "Holbein would have, very early on, witnessed some of Henry's brutal treatments of dissenters," says Moyle.

Survival at this turbulent time meant keeping your eyes and ears open, and your mouth firmly closed. "One of the reasons why he was so successful, is he must have been the embodiment of discretion," says Moyle. "I suspect he did overhear an awful lot, and perhaps people unburdened themselves to him, a bit like a hairdresser."

Navigating a treacherous terrain

Holbein deftly navigated the court's shifting sands, moving stealthily between Protestant reformers and Catholics as they fell in and out of favour. He painted Sir Thomas More and the Duke of Norfolk (Thomas Howard), explains Moyle, as well as their arch-rival Thomas Cromwell – all three eventually locked up in Henry's gruesome Tower of London, while Holbein slipped quietly onto the next client, ever-conscious, no doubt, of the family he had to feed back in Basel, and later also in London.

Holbein's work required a dancing act between verisimilitude and diplomacy. At times, he appears to flatter his sitters. A comparison of the preparatory drawing and the finished portrait of Sir Henry Guildford reveals that Holbein elongated Guildford's face, making Guildford appear, says Heard, "a much more authoritative, much more magnificent and a much more powerful figure".

Elsewhere, there are hints of his antipathy. He makes no attempt to disguise the deep tuberculosis scar on the neck of Sir Richard Southwell, for example, and places him in a rather haughty and unsympathetic pose. Southwell was "a very unpleasant man known for betraying a number of his friends… and Holbein does capture something of that ambition and arrogance," says Heard. Yet, here − as with the imagery he frequently created for factions − he was inscrutable. "One of the reasons why I think Holbein survived is that he was a complete master of ambiguity in terms of messaging," says Moyle.

Holbein's diplomacy was not just in his depictions. The German-speaking artist also played a role in building strategic alliances abroad. The unparalleled verisimilitude of his work saw him acting as a matchmaker to the monarch. Employed as a sort of Tinder for Tudors, he was tasked with painting the portraits of potential wives across Europe in a bid to safeguard the future of the throne and form familial connections with potential enemies overseas. Thomas Cromwell commissioned him to paint a portrait of the 16-year-old widow Christina of Denmark after the death of Henry VIII's third wife Jane Seymour, and the image piqued the King's interest when he was looking for a new bride – although the marriage proposal didn't materialise for political and practical reasons.

But his artworks would shed blood. Holbein was sent to paint Anne of Cleves and her younger sister, both of whom were candidates to be the fourth wife of Henry VIII, and instructed to portray them faithfully. Even so, the rather dull Anne did not live up to her portrait, though Holbein's expressionless front-facing rendition perhaps hinted at a certain plainness. The King reluctantly took her as his wife, but soon found pretexts to dissolve the marriage and to execute Cromwell, who he blamed for the debacle.

Holbein's survival of the episode speaks to his indispensability to the King. "Art was soft power," says Moyle. In securing Leonardo da Vinci as court painter, she explains, Francis I of France earnt cultural kudos throughout Europe. England, meanwhile, was still considered a nation of boors, but Holbein changed that. "You have to see Holbein's tenure at the court in terms of Henry realising he's got his Leonardo," says Moyle.

Paintings were also powerful tools of propaganda. Sadly lost but widely copied, Holbein's bombastic, life-size portrait of Henry VIII (1537), an assertion of prerogative and potency with an oversized codpiece at its centre, was an unambivalent attempt to shore up the King's monarchic authority and strike fear into the heart of his opponents at a time when he had just declared himself the head of the Church of England.  

With illiteracy commonplace, artworks had a cultural currency that it is hard to imagine today, explains Moyle. "Paintings were events: they were held behind curtains and revealed." They were also powerful diplomatic gifts, sometimes exchanged with a former enemy or given to clients and associates, says Moyle, as "an expression of love and allegiance". Holbein's portrait of baby Prince Edward (1538) gifted to the King is a case in point, representing both gratitude for his patronage and, in its echoes of Da Vinci's Salvator Mundi, tacit support for Henry's heir as a future leader of Christianity.