The TSP4 dating from 1936 is a screened pentode for RF or VF (video frequency) amplification typically for television use. The TSP4 was one of the first valves developed for the (then) very high frequencies required for high definition television.
As was standard for such valves the maximum separation between anode and control grid circuits was achieved by taking g1 to the top cap.
The classic envelope is 42 mm in diameter and, excluding the B7 base pins, is 112 mm tall.
References: Datasheet & 1043. Type TSP4 was first introduced in 1936.