its title, it was originally to have been set in the 30th century, in the year 2962. This was subsequently changed to 2062. At the same time, the "United States Space Patrol" became the "World Space Patrol" and the name of Colonel Zodiac's spaceship (as well as the series itself) was changed first to Nova X 100, then Fireball XL5. The "XL" of the final title was taken from "Castrol XL" engine oil. Thirty-seven of the series' 39 episodes were written by Alan Fennell, Anthony Marriott or Dennis Spooner, all newcomers to the APF productions. (Spooner, however, had submitted unfilmed scripts for Supercar.) Script supervision was performed by series co-creators and voice artists Gerry and Sylvia Anderson, who also wrote the first episode ("Planet 46") and "Space Monster". Filming at APF's studios on the Slough Trading Estate began in February 1962. Three stages were used: two for puppet filming (permanent sets on one stage, one-offs on the other) and another for special effects. To speed up production, two puppet filming units were created to allow episodes to be shot in pairs by different crews, who alternated on the first two stages while the effects crew used the third. The production of each episode consisted of a week's principal photography on the main puppet stage followed by inserts-filming on the secondary stage, coinciding with two weeks of effects shooting. After a unit vacated one of the puppet stages, it was set up for the other unit to start or resume filming on another episode. Characters and voice-recording The concept brochure for Century 21 described Colonel Zodiac and Dr Venus as the "Mr and Miss America" of 2962. Venus' face was modelled on her voice actor, Sylvia Anderson. Character dialogue was recorded at a studio in Borehamwood. Robert the Robot had a Perspex body with a head adapted from a plastic tumbler. He was the only regular in a Gerry Anderson puppet series to be voiced by Anderson himself, who "spoke" the robot's lines (as well as those of supporting robot characters) through an artificial larynx. As remembered by Anderson in a deleted scene of the documentary Filmed in Supermarionation (2014): Anderson also noted that due to the silent or aspirate nature of the letter "h", the larynx did not register its vocalisation; thus, Robert's customary cry of "On our way home!" was rendered as "ON-OUR-WAY-'OME!". Daniel O'Brien, author of SF:UK –