This CRT is a mystery. It has the B12D base and four Volt heater of the WWII tubes but also features an optically flat screen. Flat glass screens were not possible in the early 1940's due to limitations in the materials available.
The internal coating behind the screen is the usual Aquadag colloidal graphite connected to the final anode. The two sets of deflection plates are connected to the base rather than being brought-out to side contacts.
In fact this looks a lot like an upgraded VCR138A or CV1587 and has the same base connections and shares a maximum screen diameter of 88 mm.
The base connections fixed to the tube. Here the Type designation can be read as S38/113 it is the 8 or B that is hard to distinguish.
The coating and flat screen.
The electron gun and Y plates. The X plates are hidden under the final anode coating.
The B12D base and locating key.
The flat screen.
The end window envelope neck is 71 mm in diameter and, including the B12D base pins, is 335 mm tall.
