This serial was based on The Cybernauts, first broadcast in 1965.
The original television script was written by Philip Levene, and the
episode featured Patrick Macnee as John Steed and Diana Rigg as Emma Peel.
The only major change in this adaptation is that
the robots are called Pabulum Robots rather than the TV name -
Dr. Armstrong, evil genius who
Cybernauts - whoops! Pabulum Robots!
As in some other radio
adaptations, Steed and Mrs. Peel receive a telephone call from Mother,
sending them in to investigate. Mother, however, is only referred to by
other characters, and does not actually appear at any point in the serial.
If you're wondering, "why call them 'Pabulum Robots'?", well a
cursory look in the dictionary will tell you that 'pabulum' means 'bland'
- clearly a comment in this instance on the featureless metal faces of the
robots. You learn something every day, you know...