The King's Bedpost is a lavishly illustrated detective story about a painting. Edward VI and the Pope is an important visual allegory of the Reformation; but when and why was it painted? Following up a sequence of clues to answer these questions, the author embarks on a fascinating and unusual voyage of historical exploration that takes the reader into book illustration and scriptural iconography, Tudor religion and politics, anti-papal propaganda and iconoclastic manoeuvres.

The discovery of some previously unrecognized pictorial sources conclusively re-dates the painting, and opens a wide-ranging discussion of art and image-making under Edward VI and Elizabeth I which moves between England and the Netherlands, linking the image-breaking movements of the two areas. Iconoclasm, and its effect on artists, is a theme which bears directly on the picture and its sources.

A large cast of characters joins the Tudor monarchs as the tale unfolds: Mary, Queen of Scots; the dukes of Norfolk and their repeating tragedy; John Foxe and his 'book of martyrs'; the Dutch humanist Hadrianus Junius; Maarten van Heemskerck, and several artists who migrated to England from the Netherlands. The painting ultimately becomes the key to a series of hitherto locked doors.