The CV10709 is the UK government specification for a valve that has the PL82 as its commercial equivalent. In this exhibit we see that the PL82 is a direct match for the procurement standard for the CV10709.
Hall Electric with their Haltron brand were re-sellers and mainly supplied for export.
This valve would normally be found in audio stages of television receivers. A pair used in push pull class AB1 would deliver 9 Watts at 4 % distortion. The peak to peak grid signal voltage would be 26 Volts and the shared anode load would be 4,000 Ohms.
The fin attached to the control grid and a view of the getter holder ring.
The pressed glass foot showing the multi-metal pins with red platinium sealed into the glass.
The top mica: the copper control grid supports connect to the cooling fin. The cathode tube is not flat across the broad face.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 71 mm tall.
References: Datasheet & 1040. Type PL82 was first introduced in 1951.