Like anyone interested in seventeenth-century history and the origins of the English Civil War, I have been aware that there were cultural issues involved. It is well known that Van Dyck created a powerful iconography of kingship through his many portraits of Charles I. Art historians have studied as an aspect of provenance the many great works of art which were acquired by Charles I from the Gonzaga collections in Mantua. And historians have described in detail Charles I’s lavish programme of building construction, his addiction to the masque as the most opulent form of court entertainment, and his acquisition of pictures redolent of popery for Henrietta Maria’s chapel in Somerset House. These activities were symptomatic of an increasing isolation of the court – vain, cosmopolitan and self-indulgent – from the King’s subjects, who were anxious to know how his extravagance was going to be paid for.

However, it was only when, four years ago, I walked into the great, barrel-vaulted, early-nineteenth-century galleries of the Prado and saw Jonathan Brown’s brilliant exhibition on the sale of Charles I’s collection that I realised the full extent of both the acquisition of great works of art by the King