The CV2902 is described as a gas filled limiting diode. The role appears to be to limit the current in a radar pulse. The top cap is the anode.
The KB/Q identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the Q identifies the maker as English Electric Valve Co., Chelmsford.
The cylinder inside the glass looks to be the anode.
The heat sink fins permanently connected to the anode.
The B7A base pins.
The wide glass tube envelope is 52 mm in diameter, and excluding the B7A base pins is 122 mm tall.
