The VR102 (an M-OV Type BL63) is a low-impedance double triode with one grid taken to the top cap. After 1941 it was renamed the CV1102.
The VR102 was supplied by M-OV to the RAF during WWII. Thanks to Frank Whitby for confirming that the VR102 was used for the R1155 receiver that was fitted to Lancaster and other bombers. As part of the direction finding (DF) circuitry, it formed the visual meter switch operating at either 30 or 80 Hz. Its output fed the twin-needled Visual Indicator and one of these instruments was usually fitted on the top of the cockpit instrument panel.
A description of this clever circuit, designed by the Marconi Wireless & Telegraph Co. is given in the Manual for the R1155 (AP2548A Volume I Chapter 2). This can be seen on the Vintage and Military Amateur Radio Society's website.
The underside of one triode showing the insulated heater passing many times through the rectangular cathode.
Top view with the grid of the left triode connected to the top-cap. The close pitch of the grid can be partly seen through the mica disc.
The classic envelope is 45 mm in diameter and, excluding the IO base pins, is 117 mm tall.
References: Data-sheet & 1040. Type VR102 was first introduced in 1939.