The CV450 is an output pentode based on the Mullard EL38. In this case it is a Mullard valve.
The remains of the Mullard label
The flat cathode with copper supports for the control grid to the side, followed by the two outer grids. Ceramic insulators add extra protection from the high peak voltages found in TV line output stages during flyback and thus collapse of the magnetic field in the scan coils.
The classic envelope is 43 mm in diameter and, excluding the IO base pins, is 119 mm tall.
Reference: Data-sheet. Type CV450 was first introduced in 1946. See also1946 adverts.
