The PCL805 triode pentode was purpose designed as a domestic television receiver frame output stage. The original design was the PCL85.
Granada started as a UK ITV broadcast franchise and expanded into television rental. Early colour televisions were expensive and prone to needing servicing and in the UK a large rental market developed that later included video tape recorders. Granada did not make valves but having their own branding did limit the number of valves that found their way into resale.
The pentode on the left and the diminutive triode on the right.
Face view of the anode.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 71 mm tall.
References: Datasheet & 3002. Type PCL805 was first introduced in 1968.