The 30L15 is a low impedance high gain double triode. The low voltage high current suggests a low noise design. The 30L15 was designed for cascode RF amplifier use in the front end stage of VHF television tuners.
The two sections with the screen between them.
A UK product. Note the holes in the end walls of the anode.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 47 mm tall.
References: Datasheet & 1040. Type 30L15 was first introduced in 1960.