01
Origins
Riley's 12/4 family of the mid-1930s was built around one of the great pre-war engine designs: twin camshafts mounted high in the block, short pushrods, and hemispherical combustion chambers — valvegear sophistication without the fragility of an overhead-cam conversion. In 1.5-litre 12/4 form it powered a range of saloons and sports models whose names — Falcon, Kestrel, Sprite — matched their light, eager character, and the Sprite variants took class honours in serious competition. The engine's finest hour came at one remove: it formed the basis of the ERA voiturette racers that carried British single-seater hopes through the late 1930s. Riley overreached commercially and fell to the Nuffield Organisation in 1938, but the 12/4's engine architecture survived deep into the post-war RM cars — the heart of the marque, outliving its independence.
1934 Riley 124 Kestrel saloon · Sicnag · CC BY 2.0
