Charles I is not quite the most recognisable of English sovereigns. Henry VIII, Elizabeth I, even Queen Victoria are more immediately familiar. But Charles is the connoisseur’s king, the man who brought to the benighted British Isles the light of the Italian Renaissance, the monarch whose court nurtured a mode of portraiture that, refined in subsequent centuries by Reynolds, Gainsborough, Lawrence and Sargent, came to pass for something distinctively English. The birth of a national style, as the exhibition ‘Charles I: King and Collector’ makes clear, was far from his intention. The monarch that emerges from the Royal Academy’s luxuriant though partial re-creation of his collection – with an emphasis very much on painting, to the neglect of other art forms – was one set on becoming a European prince of the first order. Art was a means to that end.

Charles’s father, James I, had sought to make his mark on the page, penning treatises on such idiosyncratic subjects as sorcery and smoking in a quaint Scots-English mishmash comprehended by few within his own realm, let alone abroad. James sought to raise his eldest son, Henry, in his own likeness, entrusting his schooling to a brains trust of scholars. Charles, who only became heir to the throne following Henry’s death in 1612, was not afforded (or, more to the point, was spared) the literary education their father had concocted for his first-born son. One consequence was that he was drawn less to words than to images, a medium that transcended language.

Unusually for a royal prince at the time, Charles topped off his schooling with something akin to a grand tour. In 1623, he and James I’s favourite, the Duke of Buckingham, set out, via France, for Spain, home of Europe’s most sumptuous court. The object of this expedition, admittedly, was not to deepen his appreciation of art but to secure the hand of the Infanta Maria. It failed in its principal purpose. But it did expose Charles to a court aesthetic quite different from the free-for-all his father had brought from Edinburgh to London.

Charles arrived back from Spain with works by Titian and Veronese, artists who were then barely known in England, except through the writings of Vasari. Yet Charles picked up much more than a few old masters in Spain. He also developed a deep regard for the order, ceremoniousness and majesty of the Spanish court. Indeed, to isolate his collecting from the other fruits of his Spanish sojourn, as this exhibition unavoidably does, is to overlook the general effects of the trip on his notions of kingship. During the 1630s, Charles oversaw a reformation of his court, introducing a sober protocolism modelled on the Spanish paradigm.

James I was intent on being an original – a philosopher king of the Platonic kind. Charles, who grew up tongue-tied and self-conscious at his father’s lubricious court, was, by contrast, content to conform in matters cultural. But what did it mean for an early modern prince to conform? Obviously, it could not mean aping the manners of his subjects, who were by definition his inferiors. The only possible models were his fellow sovereigns, his sole peers in the world. Collecting was one way for Charles to place himself in the mainstream of European royalty. Early in his reign, an off-the-shelf solution presented itself when the bankrupt dukes of Mantua offered up their hoard of Renaissance masterpieces for sale. The acquisition – the torturous ins and outs of which are described in an excellent essay by Barbara Furlotti and Guido Rebecchini – turned Charles into a collector of the first rank.

The centrepiece was Mantegna’s Triumphs of Caesar series, which rightly sits at the heart of this exhibition. Vasari had lauded these works and Duke Vincenzo II Gonzaga fought to hang on to them, even when his Correggios and Tintorettos were being crated up. But he died in December 1627 and the succession of an insecure cousin needful of further cash removed the final obstacle to their sale. The acquisition of the set was a coup for Charles, not least because of its pedigree. The Gonzagas may have been mere dukes, but their court had been one of the most brilliant of the Renaissance. In addition, the subject of Mantegna’s paintings linked Charles’s kingship to an even more illustrious example of political eminence in European history.

In his patronage, too, Charles looked to continental precedents. This was by no means inevitable. In Whitehall Palace, which burned down in 1698, Charles could have daily admired the murals executed by Holbein for Henry VIII. He even acquired a good number of canvases by Holbein, several of them reassembled here, so was not indifferent to the art of earlier English courts. Yet it was paintings associated with continental courts that were Charles’s primary inspiration. As Rebecchini makes clear in another essay, on Charles’s visit to Spain, this meant above all the works that Titian had produced for Emperor Charles V, the style of which Van Dyck, who became principal painter in ordinary to the king in 1632, was encouraged to imitate.

The switch in styles that Van Dyck instigated becomes apparent by comparing Mytens’s stiff-looking 1628 full-length portrait of the king with the freer, more expressive composition of the same type that Van Dyck completed eight years later. Desmond Shawe-Taylor observes that, prior to Van Dyck, portraitists in England had been preoccupied with capturing the finery that their subjects wore. That is not to say that Van Dyck was unconcerned with such details: the brilliant portrait Charles I in the Hunting Field, showing the king in tilted hat and creased riding breeches, is testament enough to that. But Van Dyck’s innovation was to take the king out of court and into nature, suggesting a symbiotic relationship between the two.

If the style of painting that Van Dyck was urged to emulate was European, so also was the subject matter that his works addressed. One of his most celebrated works, The Greate Peece of 1632, shows Charles seated with the regalia beside him, his wife, Henrietta Maria, gazing devotedly at him, their two children close at hand and the silhouette of Westminster Hall emerging from the gloaming behind them. This, with hyperactive hindsight, is interpreted here as a token of Charles’s subordination of Parliament. But Charles had dissolved Parliament only in 1629. It’s worth remembering that, at the time, intervals of four or more years between Parliaments were not unusual. The title surely refers to the peace Charles concluded with France in 1629 and Spain in 1630, the first of which had the benefit of restoring conjugal harmony between the king and his French-born wife. Van Dyck’s double portrait of a contented Charles and Henrietta Maria exchanging a laurel wreath and an olive branch, also of 1632, bears this out.

The Greate Peece hung in the vista of the Long Gallery at Whitehall. It is clear from the top billing it received in Abraham van der Doort’s inventory of 1639 – which, along with a Parliamentary inventory of 1649, forms the main source for this exhibition – that the king considered it a major work. But its subject matter was not unique. Peace is a recurring theme in the paintings here. Rubens’s didactic Minerva Protects Pax from Mars, painted for Charles in around 1630, alludes to the plenitude that peace will bring – something of an exaggeration in England’s case, for war with France and Spain had become unaffordable and solvency was the most that could be wished for in the short term. Nevertheless, with the Thirty Years’ War laying waste to central Europe, this was a good place to start.

Peacemaking was not merely sound policy. It was also the monarch’s vocation, the obverse of his prerogative power to wage war, a privilege peculiar in Europe to the college of sovereigns. This yin and yang of kingship is celebrated in Van Dyck’s two great equestrian portraits of Charles. In both cases he appears in armour, yet with bucolic countryside rather than blood-drenched battlefields unfolding behind him. This, if anything, was the main dig at Parliament in Van Dyck’s work. MPs might carp all they like about expenditure on foreign campaigns, but decisions of war and peace remained the king’s birthright.

There was another, more direct link between art and policy, as Gregory Martin’s essay on Rubens reminds us. Painters, agents and dealers were international figures, forever moving from court to court. Sometimes, as in the case of Rubens, they were accredited diplomats; at other times, they were informal conduits of intelligence and information. Peace increased this human concourse: it meant more opportunities to exchange artworks (with a few exceptions, the works in this exhibition were acquired between 1629 and 1642), to attract painters and to show off one’s collection to foreign travellers. The Greate Peece was the first work visitors to court saw; the wealth of the king’s collection beyond attested to the virtues of his peace policy. Art, Jeremy Wood observes in an essay on connoisseurship in England, provided an entry to Charles’s court. Many of those who prospered there, such as Thomas, Earl of Arundel, and Endymion Porter, were themselves energetic patrons and collectors. It’s no coincidence that they were among the strongest proponents of peace with England’s neighbours, or that they were well travelled on the Continent.

The start of the Civil War marked the end of Charles’s career as a serious collector. England closed in on itself and the peace dividend expired. Notoriously, in 1649 the victorious Parliamentarians barely waited until Charles’s body was cold before flogging off his collection, which was far too Catholic for their tastes. In an act of macabre humour, they also forced Charles to pass on the way to his execution beneath Rubens’s The Apotheosis of James I on the Banqueting House ceiling, which he had commissioned in 1629. But the exhibition does not, thankfully, turn the story of Charles’s collection into a grand tragedy. It instead serves as a parable of the timeless conjunction of peace, culture and cosmopolitanism.