The painting was described in the inventory of March 1928 as ‘George Villiers Duke of Buckingham three-quarter length, wearing armour, lace ruff and cuffs and insignia of Knight of Malta holding plumed helmet and baton of office’, an identification that suggests its earlier provenance was unknown. It has since been established that the sitter is Louis XIII (1601–1643), son of Henry IV and Marie de’ Medici. A weak and ineffective king, Louis was dominated by his mother and elder courtiers. Perhaps in an effort to counter his poor public image, he is depicted adopting a martial persona, in a suit of polished armour, grasping a commander’s baton and wearing the chivalric Order of St Esprit. The present portrait shows strong formal similarities to, and may well be based on, Rubens’s depiction of Louis XIII dating from 1622 (fig. 1), as a comparison suggests.