The EBC33 is a double diode triode with a common cathode. The design dates from the late 1930s (1937-1940). This is another case of a valve that was released with the continental Ct8 base as well as the IO base. SeeEBC3 for the Ct8 version. Both had identical electrical characteristics.
Typically such multiple valves would be used in superhet receivers at the end of the IF amplification chain. One diode would produce the AGC voltage and the other would be used as the AM signal demodulator feeding into the triode as a first audio amplifier.
The date last tested was 22/10/1998. The box was Ever Ready and the valve within from Mullard. Mullard made valves for Ever Ready but with the Ever Ready livery.
The reverse is plain metallic paint.
The classic envelope is 30 mm in diameter and, excluding the IO base pins, is 85 mm tall.
References: Data-sheet, 1040, 1043 & 3002. Type EBC33 was first introduced in 1938.