The EBC81 is a double diode triode with the triode designed for audio amplification. The diodes share the same cathode as the triode and would be used for signal detection and AGC rectification.
It was believed that Mullard used yellow paint to echo the gold paint used in the 1930's. The yellow paint was used for the Mullard golden jubilee in 1969. In 1975 another drum of the paint was found at the Blackburn plant and this was subsequently used. BUT this valve carries the later logo and was made overseas. This suggests that another supplier also used yellow paint for Mullard valves.
The triode is at the top with the diodes below. Through the hole in the expanded metal screen the control grid winding can be seen.
The focus is on the grid.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 53 mm tall.
References: Datasheet & 1040. Type EBC81 was first introduced in 1954.