This TV series only exists nowadays as a black-and-white film recording. The color video tape copy was lost many years ago at a time when it was common to reuse video tape once it had been broadcast.
The concept of anyone outside the broadcasting industry having access to a video recorder to beam programmes into a school was rather revolutionary in 1972.
The video recorder used by "The Voice of Truth" was a Sony CV-2000, one of the first domestic video recorders available. It was released in 1965 and was only capable of black-and-white recording. In Episode #1.9 (1972) there is a brief view of the video camera that was sold as an accessory with the CV-2000.
According to the Ordnance Survey map which Forrester and Jessie Ruggles use in Episode #1.8 (1972), Redlow and the air base are somewhere south-east of Grantham in Lincolnshire; Jessie points to the village of Bourne and refers to it as "the village centre".