1931 marked the inception of the Speed 20, and it heralded a new departure for Alvis.

With a double beam axled chassis, longer and lower than previous models, its appearance rivalled that of Swallow Sidecar’s SS1.

At its heart was an enlarged and modified 2,511cc version of the Silver Eagle’s six cylinder engine, and when a synchromesh gearbox was introduced for the 1934 model year it marked the first such fitment on a British car; previously the gearbox had also been in unit with the engine.

At the same time the Speed 20 was also improved with independent front suspension using a transverse leaf spring and wishbones, while later models boasted an increase in capacity to 2,762cc to cope with heavier touring coachwork.

In either guise the Alvis Speed 20 was a formidable performer for the time, capable of 80mph, achieving 0-60mph in about 15 seconds via its four speed transmission, and was ranked as one of the best and most refined sports cars available.

It also proved popular and...