Numbers first, because with the Austin 12/6 they are the story: 1496 or 1711 cc Straight-6, 24 bhp @2,400 rpm. British Motor Corporation built from 1931 to 1937, when streamlining and independent suspension were arriving together.
Where it came from
The Austin Light Twelve-Six is a 14 tax horsepower car with a 1496 cc engine that was introduced by Austin in January 1931. It was named by Austin Light Twelve to separate it from the well-established Austin Twelve. The general public then dubbed the original Twelve Heavy Twelve but Austin never used that name.
The Light Twelve-Six remained in production until 1936. In August 1936 the Austin Goodwood 14 (of 16 tax horsepower) with its "sound insulated coachwork" took the place of the Twelve-Six saloons. The tourers remained available. The Goodwood was also available as a separate chassis.
Under the skin
Under the skin sits 1496 or 1711 cc Straight-6; it is rated at 24 bhp @2,400 rpm. Kerb weight is Saloon 19+1/2 long cwt. The gearbox is a single-plate dry clutch, 3-speed centrally controlled gearbox taking the drive through an open propeller shaft to the spiral bevel driven three-quarter floating rear axle.. The wheelbase is 106 in / Track 4' 2", 50 in. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
In context
Where it sits in British Motor Corporation's history is not in doubt: the variant of Austin Twelve came before it; the Austin Fourteen Goodwood followed it; it was built at Longbridge Plant. On a showroom list of its day it stood against the Vauxhall Cadet. Nearby in the British Motor Corporation catalogue sit the Austin 10 and the Austin 12.
The money
MotorJury scores cars on the United States complaint and recall record, and the Austin 12/6 has none: too old, too rare, or never sold there. Its value today is a collector's question, decided by provenance and condition rather than by a class average.