Donald Healey was a British aircraft and automobile engineer who became a rally driver, starting with a Buick in 1921. He later worked as Technical Director for Triumph Motor Company from 1934 to 1939. During World War II, Healey designed aero engine carburettors at Triumph and later worked on military vehicles at Humber Limited, while also planning a high performance car for the post-war market.
In 1946, Healey formed the Donald Healey Motor Company in Warwick, England, alongside Benjamin Bowden, A.C. Sampietro, James Watt, and his son Geoff. Sampietro designed the chassis that became the basis for the company’s subsequent cars, while Bowden designed the curvaceous bodywork used on earlier models. In 1948, a change in purchase tax rates created a market for a modestly priced high performance car, leading to the development of the Silverstone, initially priced at £975. The Silverstone drew inspiration from the earlier prototype Healey X 1, nicknamed the Red Bug.
The Silverstone’s roadster body was designed by Len Hodges, who rounded the rear and cut a slot for the spare wheel to act as a bumper. The body was produced in light alloy by Abbey Panel and Sheet Metal Co., Ltd. of Coventry, at a cost of £150 per copy. It was the first Healey to use a tubular metal structure to support the body, rather than a timber framework. The chassis was a revision of Sampietro’s original 1945 design, a ladder chassis with central cruciform bracing, shortened for the Silverstone. Two versions of the chassis were produced: the original 1949 D-Type, and the later E-Type, which was wider and featured a bench seat and a bonnet scoop.
The Silverstone used Healey’s signature trailing arm front suspension, designed by Sampietro, with coil springs and lever arm dampers. The rear suspension incorporated Riley parts, including a torque tube driveline and live axle, located by radius rods and a Panhard rod, and suspended on coil springs and Woodhead-Monroe telescopic dampers. Power came from the Riley "Big Four" inline four cylinder engine, producing 104 hp with a manifold of Healey’s own design and two SU H4 carburettors. This engine was mated to a four-speed Riley manual transmission.
In 1950, Tommy Wisdom drove a Silverstone to a new world one hour speed record at Montlhéry, France. The Silverstone’s popularity led to instances of other Warwick Healey cars being rebodied as Silverstone conversions. In December 1949, Donald Healey sought a supply of Cadillac V8 engines in America, which led to a collaboration with George W. Mason of Nash-Kelvinator and the development of the Nash-Healey, built on a further evolution of the Healey chassis. The Alvis-Healey was also produced in Britain, using an Alvis inline six cylinder engine. Briggs Cunningham installed a Cadillac V8 into a Silverstone chassis (D15) and raced it in the United States, achieving a second-place finish at Palm Beach in 1950 and another second at Watkins Glen later that year. Another Silverstone, X 4, was also fitted with a Cadillac V8, but development ceased when GM declined to supply further engines.