Pourbus had painted Louis regularly over approximately a decade whilst at the French royal court, however the present design is unique, with no other known versions. Whilst in his portrayals of the king as a child he depicted the younger Louis in blue or red silk costumes, from adolescence, as here, he wears white silk with gold embroidery, redolent of his celestial kingly status. In our portrait, the costume itself is of an entirely new fashion – the doublet is of watered white silk, with multiple ripples and reflections, rather than the ‘slashes’ of his previous doublets. As well as golden embroidery there are additional and manifold gold buttons. Pourbus has relished every detail, from the clustered layers of lace in his newly rounded ruff, to the ironed fold in his blue sash from which is suspended the badge of the order of Saint Esprit. The young king retains the lovelock that first appeared in a portrait from 1617, but now his nascent moustache is apparent.

Our painting is believed to have been in the collection of the Dukes of Infantado, Spain, for many generations, one of the six most important Dukedoms in Spain. The family brought together two of the greatest Spanish historic collections, those of the Dukes of Lerma and the Dukes of Infantado, which were united following the marriage in 1686 of Doña Luisa Mendoza and the 1st Duke of Lerma. The portrait may then have entered the Osuna collection during the time of Pedro Nuñez Girón y Velasco Guzmán y Tovar, Duke of Osuna (1574 – 1624), who served Philip III as Capitán General and Viceroy to the kings of Sicily (1610 – 1616) and Naples (1616 – 1620). These last dates coincide with that of our portrait, which significantly is inscribed to the reverse in Italian. Pedro Nuñez Girón de Velasco, known as the Gran Duque de Osuna, was one of the most outstanding personalities in Italy at this time. His relationship with the Duke of Lerma, favourite of Philip III, was very close and extended even to the point of marrying his son and heir, Juan Tellez Girón, to the grand-daughter of the Duke of Lerma and daughter of the Marquis of Uceda. As with the earlier portrait of his younger sister Elisabeth, painted some ten years earlier, Pourbus sets the sitter against a rich crimson satin background.