The CV1065 is an HF pentode with an MO base - thus a Mazda valve. Other prior names for the CV1065 were VR65, ARP36 and the GPO POVT200. The prototype was a modified SP41. The SP41 has a 4 Volt heater and the SP61 a 6.3 Volt heater.
This exhibit has been overprinted with the reseller name.
The reverse carries the stores stamp AETLW 1.
The top mica components are all that are visible. The cathode is a rectangle and the supports for the three wire grids can be seen.
The classic envelope is 32 mm in diameter, and excluding the MO base pins is 81 mm tall.
Reference: Datasheet. Type CV1065 was first introduced in 1941.