For Four Feather Falls and the first series of Supercar, there was only a single puppet for each character. However, with the second series of Supercar it was decided to produce an identical twin in order to enable different units to shoot simultaneously. Fireball XL5 expanded on this slightly, by providing certain characters with a head that could blink. For Stingray though, this innovation was taken a step further. In June 1963, Kine Weekly reported: "A former objection to puppets is that, no matter what they are saying, grave or gay, their expressions have remained unchanged; one might see Venus imparting the gravest of news, still with her habitual smile. This is now being remedied." This remedy came in the form of four separate heads allowing the characters to emote. There was a 'smiler', a 'frowner', a 'blinker' and, of course, a neutral head. 

 

This section presents a gallery of the full variety of heads used for Thunderbirds Series One. As you can see, even beyond the change of expressions, there is a degree of natural variation which comes with them being hand made - especially noticeable with the neutral twin heads.