The DAC32 is a dry battery diode triode that was designed for AM broadcast radio reception. Mullard (valve suppliers to Ever Ready) describe this valve as a medium gain triode for use as an AF voltage amplifier combined with a single diode for signal or AVC (AGC) rectification.
The filament power is very low and consequently the valve is rated for a very low anode current.
The single strand filament passes through the triode at the top and then the screening box that houses the single diode anode.
In this image the triode grid can be seen emerging from the anode. The stout wire entering the right of the lower screening box is the diode anode. On the left can be seen a tape that connects the lower filament support to the screening box.
The wide glass tube envelope is 30 mm in diameter and excluding the IO base pins it is 86 mm tall.