Come not between the dragon and his wrath. Come not between the artist and his temperament. Sandy Naime, director of the National Portrait Gallery, has stepped in where others fear to tread. The gallery commissioned Michael Reynolds to paint Bernard Haitink, the conductor, for its collection. But when the portrait was delivered, Mr Naime found the format unsatisfactory. He opined that there was too much desk in the foreground, and that Haitink’s head needed sharper delineation. Artists are hardened to such comments from critics, about whom they feel much as a lamppost feels about dogs. But to receive such pedagogic discipline from an official apparatchik is gall and wormwood.

This is just the latest example of the eternal wars between art and brass. Patrons of medieval artists demanded to have themselves portrayed kneeling among the Wise Men, whatever the tempera of the artist. For centuries critics have argued about the mysterious smile on the face of Mona Lisa. But there is no need to speculate that, like the vampire, she has been dead many times, and learnt the secrets of the grave. Surely it is more likely that Francesco del Giocondo made Leonardo da Vinci repaint his wife so often that she ended up looking bored? Who can fathom the imagery of Primavera? Why not the Medicis advising Botticelli to elaborate his format? Might Whistlejacket actually be a portrait of George III himself, exclaiming: “How much longer do I have to hold this pose?”, after orders for sharper delineation from Stubbs’s patron, Lord Rockingham? He who pays the whistler calls the tune. This may explain why Whistler’s mother looks so grey.