The 11D3 is a double diode triode receiver valve designed for universal sets, that is with a series heater chain and no mains transformer and dates to 1934 when DC mains still existed and the National AC Grid was being developed.
It is interesting that this should have been the valve featured on the playing cards that Brimar issued as advertising material. It seems branded playing cards were popular in the mid 1930's.
The triode is at the top with the grid taken to the top cap. The screening box enclosing the diode anodes is below.
The diode anodes are just vertical rods. The screening box is connected to the cathode.
The triode anode can be seen to form a cylinder to enclose the grid and cathode. The insulated heated wire passes through the cathode many times.
The classic envelope is 38 mm in diameter, and excluding the B7 base pins is 96 mm tall.
References: Data-sheet, 1040 & 1043. Type 11D3 was first introduced in 1934.