The SPV was designed by special effects director Derek Meddings on the basis of a brief description given in the Andersons' original script for the first episode, which specified only that the SPV was a high-speed armoured vehicle with reversed seating (and thus no windscreen) and a removable "lightweight power unit". Noting that the occupants faced backwards and viewed the road through a TV monitor, Meddings said that "all meant to me was that I could design the vehicle without windows." For added realism, these were replaced with grilles and air vents. To fulfil his vision of a "menacing, shark-like" assault vehicle, Meddings added a tail fin to the design. He also incorporated a broad front bumper, intended to be shock-absorbent, and five pairs of wheels (in two sizes), as he thought that vehicles with more wheels "looked more interesting on screen." He said that he was pleased with the SPV design because he believed that it "could be filmed from any angle".