This picture was probably painted as a complete 'modello' (preparatory painting or model) for the great equestrian portrait of Charles I now in the National Gallery, London. It is possible to see the alterations made by Van Dyck to the position of the King's right arm and shoulder, and to the insignia of the Garter. The head of the King is most sensitively painted, and almost certainly from life.

Van Dyck's design appears to be a reinterpretation of Titian's famous equestrian portrait of Charles V in the Prado, Madrid. However, it is possible that the artist was also influenced by sixteenth and early seventeenth century English engraved portraits. The painting has been much copied, even into the 18th century.