The CV1111 is a high vacuum half wave rectifier. The prototype was the V1907.
The KB/E identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the E identifies the maker as Thorn-AEI, Brimsdown.
The maximum PIV is 14 kV and so the anode has the extra insulation afforded by the ceramic inserts into the mica discs.
The oxide coated filament has three loops with each held taut by a coil tension spring.
A closer view of the filament. The distance between the filament and the anode is large due to the high voltages.
The classic envelope is 50 mm in diameter, and excluding the B4 base pins is 126 mm tall.