The NR44 (later renamed CV1168) is an audio output triode based on the PX4. For the General Post Office this design was called POVT131.
The envelope contains the Admiralty Pattern number of 3832 as well as NR44 and a serial number.
The base cap cement has obviously been augmented by this plastic band. The band is continuous and is not just adhesive tape. It looks to be heat shrink plastic.
The anode is much wider than the front to back dimension.
Some enhancement to bring out the envelope lettering.
The face view showing the four filament loops and their tensioning springs at the top.
The dome reveals the manufacturer - Cossor. However, the base cap is distinctly M-OV and there was a connection between the companies. Government valves had to be made by several suppliers and it is possible that parts were exchanged.
The filament springs and top mica.
The right side oxide coated filament loop can be seen in the hook of the helical tensioning spring.
The classic envelope is 50 mm in diameter and, excluding the B4 base pins, is 118 mm tall.
