The LP2 battery triode was a popular design and very similar valves were produced by several companies. As an audio output valve it produced 0.18 Watts. The 2.0 V filament was designed to be supplied from a single lead-acid accumulator.
Our other LP2 exhibits have the earlier balloon envelope. One with a slanted electrode assembly and one LP2 with vertical electrodes.
The Marconi paper brand label.
The upper mica holds the filament tension springs. Both inverted V filaments are still intact.
The classic envelope is 41 mm in diameter and, excluding the B4 base pins, is 83 mm tall.
References: Datasheet, 1040 & 1043. Type LP2 was first introduced in 1930.