The CV4053 is a 150 Volt voltage stabiliser with flying leads. The maximum striking voltage is 180 Volts and the maximum current is 15 mA.
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 wires are integral to the glass base and here are passed through a pin straightener.
The cathode tube seam and in the centre is the anode rod.
The thin glass tube envelope is 18 mm in diameter and, excluding the base wires, is 45 mm tall.
References: Data-sheet, 1040 & 1043. Type CV4053 was first introduced in 1955. See also1955 adverts.