The Mullard EB41 is a double diode with very small inter electrode capacitance. It is possible that this valve was designed for special applications like TV and RADAR and not as a miniature replacement for the ubiquitous 6H6 family.
The anode to cathode capacitance is 0.01 pF.
The hard glass base disc can be seen clearly as the soft envelope glass is on top of it. Later miniature valves had hard glass disc inserted into the envelope tube.
The diameter of the moulded skirt is 22 mm. Within the outer screen the getter holder support is on the left and the actual diodes are confined to less than half the height of the screen.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 54 mm tall.
References: Datasheet, 3002 & 1040. Type EB41 was first introduced in 1948.