Armstrong Siddeley was formed in May 1919, when the Newcastle-based engineering group Armstrong Whitworth acquired the Coventry-based Siddeley-Deasy Motor Car Company, itself the successor to a business John Davenport Siddeley had originally founded in Coventry in 1902. The new company built luxury cars and aircraft engines side by side from its Parkside works in Coventry, an unusual dual identity that shaped much of its engineering.
The 5-litre, 30hp Thirty, launched at the 1919 merger, remained in production until 1932, an unusually long run reflecting the marque’s traditional, conservative customer base. Car production paused for the Second World War and resumed at Parkside in 1945, continuing through a series of well-regarded models including the Sapphire range of the 1950s. A final, more modern Star Sapphire arrived in 1958, but could not save the car business, and manufacturing stopped for good in 1960 when Armstrong Siddeley’s aero-engine interests merged with Bristol Aero Engines to form Bristol Siddeley. The Parkside factory has since been demolished; the Armstrong Siddeley name and remaining spares now belong to the Armstrong Siddeley Owners’ Club.