THE PROGRAMME: When Doctor Who was born to BBC1 in 1963, its purpose in life was largely educational. The device of time travel would enable the Doctor and his companions to visit periods in history which any child might learn about in the course of his or her education. For the sake of variety, and because the programme's creators were well aware of children's fascination with space travel and science fiction, each historical adventure would alternate with one set in an alien or futuristic landscape. Commissioned under the working title A Journey to Cathay, Marco Polo was the fourth Doctor Who serial to be made and shown - although, at this point in the show's development, one serial flowed into another without overarching story names (the episodes were titled individually). So far the TARDIS, carrying the mysterious Doctor, his granddaughter Susan, and her two schoolteachers who had been practically kidnapped from Earth by the old man, had moved from 1963 London to prehistoric times, then to the planet Skaro, then Outer Space, and now to 1289 Cathay. Pre-filming, for modelwork and special effects scenes as well as the final episode's fight sequence between Polo and Tegana, took place at Ealing Film Studios in January 1964. Also filmed at this time were caption shots of a parchment map detailing the caravan's route, these would accompany Polo's journal narrative in each episode. Studio recording then proceeded from January to March, with one episode per week being recorded at the BBC's Lime Grove studios in west London. The transmission of Marco Polo occasioned the first Radio Times issue to devote its cover to Doctor Who, the number dated 20 February 1964 featuring Polo, Tegana and the Doctor on the front. The incidental music for the serial was composed by Tristram Cary for an ensemble of flute/alto flute, harp and timps/percussion. Certain elements were then combined and electronically treated to createe such atmospheric cues as those accompanying the scenes in the Cave of Five Hundred Eyes. Marco Polo has the unhappy distinction of being the earliest batch of Doctor Who episodes absent from the BBC television archives. The off-air soundtrack recording, and a wealth of photographic material from the studio recordings, are the only remnants of this classic serial known to exist.