2003 Archive 
Anderson puppet artists Mary Turner and Plugg Shutt had developed stringless puppets during the period between the end of THUNDERBIRDS and startup for SCARLET; stringless puppets meant that the puppets could be controlled from underneath and thus look more natural in sitting positions, flying planes, driving cars, etc. Also, toward the end of THUNDERBIRDS, engineers John Read and Reg Hill had experienced a breakthrough in solenoid technology for the voice mechanism that enabled it to be reduced in size so it would fit inside the chest cavity rather than the head (which had always been overlarge and out of proportion to the rest of the puppet).
The combination allowed a complete redesign of the puppets to 1/3 human scale, which made them look much more realistic; at first glance, it is often difficult to tell that some of the shots in SCARLET are not of humans. The drawback was that they did not move as realistic as they looked, so many shots done of the puppets going from place to place were done on moving walkways, and other motion was often implied by changing camera angles and sounds of movement (the famous "walk down the alley" during the opening credits of SCARLET, for example, is done strictly from the point of view of the person walking; all one hears is the click of bootheels on pavement).
Puppeteers often found the perfectly proportioned marionettes harder to control when they were on strings because they were so much lighter that any movement looked highly exaggerated at that scale, destroying the illusion they were designed to create. Nevertheless, the perfectly proportioned marionettes were used for all the remaining Supermarionation productions, allowing for some interesting live action intercuts in THE SECRET SERVICE and much puppet recycling in JOE 90 and THE SECRET SERVICE.