Captain Scarlet and the Mysterons

Having overseen APF's work since the making of Supercar in 1960, Grade was keen for Supermarionation to penetrate the lucrative American market and believed that a new concept would stand a better chance of landing a network sale than a second series of Thunderbirds.

He had once been inspired by the thought of creating a live-action police drama in which the hero is unexpectedly murdered partway through the series and replaced by a new lead character.

Now returning to this idea, Anderson realised that a major selling point could be a character who is killed at the end of each episode and resurrected by the start of the next.

Aware that white light is composed of—and can be broken down into—the colours of the spectrum, he named Spectrum's leader Colonel White. thumb|left|Anderson in 2009|alt=The photograph depicts an elderly man, whose gaze is directed to the right of the camera.

According to Anderson, the Mysteron rings were inspired by a TV advertisement for wool that featured the Woolmark logo being projected onto a woman.

With "The Mysterons" as their working title, the Andersons wrote a pilot script in August 1966.