The 8D2 is an HF pentode to an RAF specification that placed a 6J7G onto a B7 base and changed the heater to a 200 mA series heater chain type. Originally the RAF Type was called the VR108 and then in 1941 the CV designation was given as CV1108.
The Brimar name and Made in England.
The screen obscures the main electrodes but at the base the multi-loop insulated heater can be seen. The heater passes through the cathode tube six times.
The classic envelope is 38 mm in diameter, and excluding the B7 base pins is 96 mm tall.
Reference: Data-sheet. Type 8D2 was first introduced in 1934. See also1934 adverts.