Mullard describe the EF41 as a variable μ RF pentode for use as an RF or IF amplifier.
In the literature Mullard state that although pins 3, 4 and 7 are internally connected together, it is recommended that the external cathode connection be made to pin 7 as this point offers the lowest connection inductance.
The locating pip is built into the glass skirt and no spigot is required. The first B8A valves had metal skirts with locating pips and employed locating spigots as well. See6F1 as an example.
The mesh screen obscures the internal structure but it looks as if the anode is formed by two plates joined by straps.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 54 mm tall.
References: Data-sheet & 1040. Type EF41 was first introduced in 1947.