Along with the Seven, the Twelve saved the ailing Austin concern, nearly 70,000 of the larger model being sold up to the end of 1930.

Launched in late 1921, the Twelve owed its success to Austin’s superior build quality and the soundness of the basic design.

The model became a byword for indestructibility, a virtue that commended itself to the London taxi trade that used the ‘Heavy’ 12/4 extensively throughout the 1930s and ’40s.

The Twelve engine was a five-bearing, magneto ignition-equipped, sidevalve four displacing 1,861cc, for which the factory claimed a maximum output of 27bhp at a lowly 2,000rpm, sufficient for 40-45mph cruising at which speed the Twelve returned around 26 miles per gallon.

Effective four-wheel brakes meant that the Twelve coped with sudden emergencies better than many of its contemporary rivals.

After the Light 12/4’s arrival in 1933, the Heavy Twelve’s days were numbered, the last example leaving the factory in 1935.

Enduringly popular, the model remains...