The CVX465 subminiature wire ended pentode is very close in characteristics to the EF72. The multiple connections to the cathode suggest that the valve was to operate at a reasonably high frequency. Mullard describe the EF72 as an RF pentode for the front end stage of communications receivers. Thus the response needs to be good to at least 30 MHz.
It is a high impedance device with moderate gain, this probably indicates use with a tuned anode load.
The hole in the anode affords a view of the three wire grids.
A slightly better view.
The thin glass tube envelope is 10 mm in diameter and, excluding the B8D base pins, is 36 mm tall.
References: Datasheet & 1040 Type CVX465 was first introduced in 1950.