The Big Pull
The Big Pull (1962) is a highly innovative BBC science-fiction series concerning an alien invasion of earth. Unlike conventional science-fiction of the Doctor Who-type, there were no monsters or humanoid aliens. In this respect it was similar to A for Andromeda.
The events occur during early space exploration. Earth came under attack by an invisible force, which took over humans in pairs; one disappears, one dies. The disappeared one emerges under alien control.
The fear grows palpable when it is realised that the number of victims is growing exponentially; the time between each attack halves each time, and the number of victims doubles. The hero, Sir Robert Nailer, realised this trend when he was following a van sporting the advertisement for a typewriter which read, "Twice the output in half the time".
Again, unusually for the genre, the series ends with widespread panic as it is realised that every effort has failed, the scientists are dead, that the whole population of the Earth will be gone within hours, and there is nothing that can be done.
The series ran over six episodes, during the time that the first ventures into space by Russian and American astronauts were taking place. As of 2015, however, no episodes exist in the archives.