The LZ319 is from the era of VHF television in the 1950s and early 1960s. The valve is a triode pentode designed to function as a mixer and local oscillator in the tuner. The B319 was the M-OV name for the corresponding double triode cascode amplifier valve found in VHF tuners at the time ITV television began on Band III in 1955 in the UK.
The pentode on the left with the smaller triode mounted at right angles to the pentode electron stream.
The remains of the Osram paper label.
The thin glass tube envelope is 21 mm in diameter and 48 mm tall, excluding the B9A base pins.
References: Data-sheet. Type LZ319 was first introduced in 1954.