The LS5B from M-OV was a dull emitter valve designed for audio amplification and especially as a driver for the LS5 and LS5A. The LS5B was a medium impedance device with the design use of being a high voltage driver.
The etched lettering is clear and sits within the standard M-OV oval.
The paper label on the side of the glass is a BBC-E-57 clearly showing that at one time this was owned by the BBC.
The nickel anode showing the flattened working faces and rounded ends.
A closer view of the grid and within the stubs of the broken filament.
The balloon envelope is 56 mm in diameter and, excluding the B4 base pins, is 108 mm tall.
References: 1043. Type LS5B was first introduced in 1927.