The Royal Hunt of the Sun took on something of a legend in its own time, as did Equus … and Amadeus…. Apart from their popularity, they share Shaffer's concern for grand, metaphysical themes rooted in dominant images and formally structured through highly-skilled stagecraft…. It is not surprising that he lists music and architecture … as his interests, and likens a good play to a piece of music, analysing thought and deepening emotion through its strict rules. 'It has to be a cathartic experience,' he says, which is what he achieved for many with the three major plays.

They are each essentially about a confrontation between two people…. Despite the different historical settings, the plays have nothing to do with history. In different ways, they are all about what Bernard Levin might describe as 'life force'—explored less successfully in The Battle of the Shrivings …, in which a hypocritical...