"Velázquez worked at the Spanish court in Madrid where he painted portraits of the royal family to hang in the palaces and be sent abroad as gifts. Demand for royal images was such that many of
these portraits were copied several times by other painters in Velázquez’s studio.
The Dulwich portrait of Philip IV is a version of an original of 1644, now in the Frick Collection, New York, which was painted by Velázquez in a makeshift studio in Catalonia while the King prepared for battle against the French. This version may have been painted by Juan Bautista del Mazo, Velázquez’s son-in-law. "