The 1930s continued to see significant advancements in motor car design leaving the 1934 Armstrong Siddeley 17hp model needing a complete redesign. To address this a completely new model, known as the 16 hp, was introduced in 1938.

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The new 16hp model had a thoroughly modern chassis, almost unitary in its design with an integrated metal floor complete with a torque tube tunnel that ran from the scuttle to the Rear Axle. The engine had a much shorter stroke leading to reduced piston speeds without reducing the power output.

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The comprehensive equipment included a front and rear hydraulic jacking system, an automatic chassis lubrication system and self-cancelling semaphore traffic indicators. Also included as standard equipment were bumpers to the front and rear, a fog lamp, a spare wheel mounted in the boot lid and a set of tools housed in a tray under the dashboard.