As you can imagine, this company does not exist any more, so I have made a page to "commemorate" it.
Rediffusion started off distributing audio by cable many years ago, probably before the second World War. When 405 line television was first introduced to the UK in 1936, there were many places where reception was impossible (notably Brighton on the South coast, which was shielded from the London transmitter by the local terrain). Rediffusion developed early cable TV technology to allow TV signals to be carried over twisted pair cable to subscribers homes.
Nowadays, we associate twisted pair with telephony, but in fact you can transport a TV signal by modulating a short wave carrier at around 3.5 MHz with vestigial sideband amplitude modulated video. When new channels were introduced, starting from 1956, Rediffusion simply used another twisted pair in the same bundle, modulating a higher frequency carrier (around 8 MHz) with VSB using the lower sideband. This approach, known as "tete-beche", minimised interference between the two carriers.
I joined the company in 1970, when we were trying to get 3 channels of 625-line colour transmission over the existing Rediffusion network. Well, it could be done, although the pictures were not too great by today's standards. The biggest nightmare was achieving electrical "balance": an imbalanced pair would lead to interference (patterning) from short wave radio signals.
I worked in the development laboratories at Chessington (SW London) on the Rediffusion Mark 1 colour TV. This was manufactured in volume on the same site in quantities of 100,000 per year. The Mark 1 TVs were distributed to rental outlets across the UK (Rediffusion stores in the high street) and were also exported to Rediffusion subsidiaries in Hong Kong, South Africa and other parts of the English-speaking world. New development work was in progress on the Mark 2 receiver when I decided to leave the company and join Hewlett-Packard. This was in 1973, by which time I had developed a patented "beam current limiter" to protect the picture tube from overload, and had learned a great deal about IF, RF and video technology.
TV technology was moving on, and much of the development work was migrating to the manufacturers of silicon LSI chips. I needed a change. It was a wise move, because the British TV manufacturing industry started to decline after that in the face of competition from the Far East. Within 10 years, the parent company of Rediffusion (BET) decided it was no longer in the TV business, closed the labs and the factory, and the building was razed to the ground.