UFO is easy to reduce to a handful of unforgettable images: silver vehicles rolling through English woodland, interceptor pilots sliding into launch chutes, women in violet wigs moving around a lunar control room, and Ed Bishop’s Commander Straker staring through everyone as if emotion were a security breach.

Those images matter. They are among the most distinctive products of British television design. Yet they can also conceal what the series is actually about.

The central invention of UFO is not the alien spacecraft. It is SHADO, the Supreme Headquarters Alien Defence Organisation, an internationally funded military and intelligence apparatus operating beneath a film studio. Its personnel have accepted extraterrestrial visitation as fact, concluded that the visitors are hostile and constructed an enormous classified system to detect, intercept and conceal every incursion. The public is not merely uninformed. It is deliberately managed.

Few television series have done more than The X-Files to teach viewers how uncertainty feels.

A frightened witness describes something impossible. Dana Scully asks what evidence survived. Fox Mulder asks who had the means and motive to make the rest disappear. An anomalous object flashes across the sky, but the photograph is blurred. An autopsy yields a strange implant, but the sample is stolen. A source offers privileged information, yet may be manipulating the investigation. Every revelation arrives with an expiration date.