John Steed and Cathy Gale’s party trick, a duet working variations on the theme of the invincibility of the British upper class, really comes into its own in Death Dispatch, the 13th broadcast episode of series two. We’re off in the sort of colonial landscape described by Graham Greene

    Things go technological in the 12th episode of series two – The Big Thinker – a tale of a big brain computer called Plato and the scientists who minister to it like Delphic virgins in white lab coats. Hanging on like grim death to the notion that Britain was