The EL32 is an octal based audio output pentode. The original production EL32 was within a classic envelope whereas this exhibit is made within a tubular envelope. This is probably a post war replacement valve.
The EL2 is electrically identical but mounted on the Ct8 side contact base that was popular in Europe but regarded as having poor reliability in the UK. Mullard say of this valve that it is a 200 mA heater valve for use in AC/DC sets or for use in car radios. The values given are for single ended use, in push pull a pair can deliver 7 W.
The inner structure is obscured by the top mica. The points pf the mica are turned over indicating an interference fit. Also it can be seen that the black coating on the inside of the envelope is applied before the electrodes are inserted. The tracks in the carbon coating have been made by the points of the top mica. The top cap connection to the control grid is the only clear aspect of the construction.
The octal pins are solder filled and this fixes the lead-out wires to the connections.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 87 mm tall.
References: Datasheet & 1043. Type EL32 was first introduced in 1940.