The PC86 is a purpose designed UHF oscillator triode for television reception. Mullard describe the PC86 as: a UHF frame-grid mixer/oscillator triode. This exhibit has the older logo and was an import. However, at the time the phrase used was Foreign Made.
The anode end view. There is an internal screen to ensure that the working electron flow is directly to the anode in front of the grid.
The working faces of the anode are very close to the grid with the heat radiating portions much further away.
The thin glass tube envelope is 21 mm in diameter and excluding the B9A base pins, is 48 mm long.
References: Datasheet & 1040. Type PC86 was first introduced in 1962.