The Mullard EL36 is a purpose designed line output valve for television receivers. Sets with parallel heaters and thus mains transformers were for professional monitor use for TV and/or radar.
Most domestic TV receivers were AC/DC designs that did not employ mains transformers and had the heaters in series across the mains. In the UK, with 240 V mains, a 300 mA heater chain was common. The PL36 was the normal valve for heater chain use.
This exhibit is of modern design with a pressed glass foot and not an old style pinch. The 1940's EL36 audio output valve lacks the top cap of the EL36 television valve with the same Type designation.
The anode supports have additional ceramic insulators because of the high peak voltages the device has to withstand. Inside the anode can be seen the beam plate that replaces the suppressor grid.
The control grid has additional heat sinking on top of the copper supports.
The top mica with flat sided cathode tube and copper supports for both wire grids.
The wide glass tube envelope is 28 mm in diameter, and excluding the IO base pins is 92 mm tall.
References: Datasheet, 3002, 1040 & 1043. Type EL36 was first introduced in 1954.