BSA, better known later for motor-bikes, issued valves in 1926 under the name BSA Standard. Standard was the brand name of STC at the time who were in turn a subsidiary of the American Western Electric company and actually made the valve.
The glass also carries the words Made in Great Britain.
At the top of the anode cylinder can be seen the grid helix and the filament tension spring and hook.
Microscope image of the electrodes. The end of the filament is held in a fold of ribbon that is then welded to the tension spring.
The thin glass tube envelope is 16 mm in diameter, and including the Peanut base pins is 63 mm tall.
References: Data & 1043. Type G125A was first introduced in 1926. See also1926 adverts.
