An English 17th-century double portrait holds many clues to its meaning

This is a big book about a minor painting — a double portrait of John Bankes, aged about 16 (the son of the Chief Justice of the Common Pleas, Sir John Bankes), and his tutor, Dr Maurice Williams. It was done in Oxford in 1643-4 by Francis Cleyn, a court painter. At the time, Oxford was the headquarters of the royalist army, and painters were busy recording for their loved ones Cavaliers who would soon be dead. In the left corner of the painting there is a copy of Galileo’s Dialogues Concerning the Two Chief World Systems, in its Latin translation, open at the frontispiece, along with a globe and a telescope. Young John holds out a drawing compass into the centre of the image, and looks out into empty space.

J.L. Heilbron devotes 500 pages to trying to make sense of this painting, but makes surprisingly little progress. What does he get wrong? First, let’s ask who the painting is for. Heilbron thinks it was intended to hang in Gray’s Inn in London, but by 1643 London was a no-go area for royalists such as the Bankes family. Young Bankes’s home was Corfe Castle. His father was with the King, caught up in the war, and his mother, the redoubtable Lady Mary Bankes, was at home, preparing to defend her castle against the Parliamentary army, a task she performed with aplomb.

The painting, then, was to hang on the walls of Corfe Castle, and its immediate audience was not Sir John but Lady Mary. Heilbron makes nothing of the compass young John holds out. He should have remembered John Donne’s ‘A Valediction: Forbidding Mourning’. There the compass stands for Donne’s promise to return safely home again, just as the compass pencil returns to the place where it began. And this tells us what the painting is really about: young John’s tutor is keeping him safe, locked up with his books, away from the court and the Cavaliers, and will bring him safely home.