Doomwatch - Season 1 Episode 12 Hear No Evil

In an effort to prevent unofficial strikes by its workforce, a company in the North of England decides to use the latest scientific discovery, and attempts to manipulate both the working and the private lives of its employees by bugging them with listening devices. However, when Quist hears of this underhanded practice he is furious and decides that the only way to stop the unethical management is to turn their own method against them.