Loosely based upon "Conglomerate", an unofficial audio production based upon Doctor Who (1963) and produced by Audio Visuals. In the original version, Nicholas Briggs played The Doctor.
The interior underground scenes where The Stranger and Miss Brown eventually discover the Cladestran combat suit were filmed in the basement of the BBC Nottingham building. The foundation pillars seen in these scenes support the building above, and actually plunged through holes in the basement floor itself. Cast and crew had to be careful they didn't fall down them during shooting.
In his Making of... article for fanzine Celestial Toyroom, Julian Boote wrote that, prior to shooting in the BBC Nottingham basement, when dressing the central core set to which the combat suit has bonded, Julian was left on his own for a time while other crew left to run errands. The fact the dimly-lit basement had sections of wall open and accessible to caves that are known to run under Nottingham and which used to be inhabited, soon got to him. While whistling to himself and working on the set kept his imagination at bay for a while, Julian became progressively more spooked by the place. What finally freaked him out was when he was startled when walking past the combat suit - worn by a mannequin and propped up against a wall.
When the combat suit begins to wriggle free of the central core to pursue The Stranger and Miss Brown, the performer inside the suit doing the wriggling was first assistant director Julian Boote.
Minor's face melting effect was achieved by first making up actor Nicholas Briggs to show Minor's initial stages of decay. The latter stages of decay involved filming a latex Minor mask, heated from behind by make-up artist Penny Bowers, who blasted it up-close with a hair dryer.