This is the second equestrian portrait of Charles to be painted by Van Dyck. Charles is depicted wearing the same suit of armour, riding a heavily muscled dun horse with a peculiarly small head. To the right, a page proffers a helmet. Charles appears as a heroic philosopher king, contemplatively surveying his domain, carrying a baton of command, with a long sword to his side, and wearing the medallion of the Sovereign of the Order of the Garter. His melancholy, distant expression was seen as a sign of wisdom. He wears the same suit of tilt armour in both equestrian paintings. A tablet tied to a branch reads – a political statement at the time, only 33 years after James had united the crowns of Scotland and England, and proclaimed himself King of Great Britain, and nearly 70 years before the Acts of Union legally created the Kingdom of Great Britain. An earlier equestrian portrait, Charles I with M. de St Antoine, c. 1633, depicts Charles under a Roman triumphal arch, clad in armour and accompanied by his riding master, Pierre Antoine Bourdon, Seigneur de St Antoine. Van Dyck painted one other major portrait of Charles I with a horse: Charles I at the Hunt, which depicts Charles standing next to a horse in civilian clothing, as if resting on a hunt, wearing a wide-brimmed Cavalier hat and leaning on a walking cane, gazing at a coastal scene; a picture of "gentlemanly nonchalance and regal assurance". Van Dyck's portraits of Charles on horseback echo the imperial tone of Titian's equestrian portrait of Emperor Charles V from 1548, itself inspired by equestrian portraits of Roman emperors. In c.1620, Van Dyck had himself painted a similar :File:Anthony Van Dick - Ritratto equestre dell'imperatore Carlo V - Google Art Project.jpg|portrait of Charles V. The composition may also borrow from Dürer’s 1513 engraving Knight, Death and the Devil. This is one of several closely contemporaneous works depicting Charles riding a horse as a means to increase his stature. Charles stood only high, and was keenly conscious of his height. In addition to the paintings, a near life-size equestrian statue of Charles I by Hubert Le Sueur was erected at Charing Cross in 1633. A design by Inigo Jones for a triumphal arch at Temple Bar was intended to bear another equestrian statue of Charles.
Painting materials
The investigation of the painting and its pigment analysis was done by scientists at the National Gallery London. Van Dyck used the usual pigments of his time such as smalt, ochres, vermilion, red lake and azurite for the rather subdued tones and subtle colours.