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.
The Standard logo and G125A Type designation.
The small diameter anode with the grid support and filament tension spring. The spring ends with a strip that folds and clamps the top of the single strand filament.
The pinch components and the base of the helical grid.
The reverse of the envelope tube carries the words Made in Gt. Britain below the STC Type designation of 4215A.
The thin glass tube envelope is 16 mm in diameter, and including the Peanut base pins is 65 mm tall.
References: 1043. Type G125A was first introduced in 1926.