Riley (Coventry) Limited
In early 1913, Percy was joined by three of his brothers (Victor, Stanley, and Allan) to focus on manufacturing entire automobiles. The works was located near Percy's Riley Engine Company. The first new model, the 17/30, was introduced at the London Motor Show that year. Soon afterwards, Stanley Riley founded yet another business, the Nero Engine Company, to produce his own 4-cylinder 10 hp (7.5 kW) car. Riley also began manufacturing aeroplane engines and became a key supplier in Britain's buildup for World War I.
In 1918, after the war, the Riley companies were restructured. Nero joined Riley (Coventry) as the sole producer of automobiles. Riley Motor Manufacturing under the control of Allan Riley became Midland Motor Bodies, a coachbuilder for Riley. Riley Engine Company continued under Percy as the engine supplier. At this time, Riley's blue diamond badge, designed by Harry Rush, also appeared. The motto was "As old as the industry, as modern as the hour."
Riley grew rapidly through the 1920s and 1930s. The Riley Engine Company produced 4-, 6-, and 8-cylinder engines, while Midland built more than a dozen different bodies. Riley models at this time included:
Introduced in 1926 in a modest but innovatively-designed fabric bodied saloon, Percy Riley's small capacity Riley 9 engine was a high revving unit; ground-breaking and ahead of its time in many respects. It has been called the most significant engine development of the 1920s. It has hemispherical combustion chambers and inclined overhead valves, with twin camshafts set high in the cylinder block, and valves operated by short pushrods. This provided power and efficiency without the servicing complexity of an overhead camshaft layout. It soon attracted the attention of tuners and builders of 'specials' for sporting purposes. One such was engineer and driver J.G. Parry-Thomas, who conceived the Riley 'Brooklands' (at first called the '9' Speed Model) in his workshops at the Brooklands racing circuit in Surrey. After Parry-Thomas was killed during a land speed record attempt in 1927, his close collaborator Reid Railton stepped in to finish the job. Officially backed by Riley, the Brooklands, along with later developments and variations such as the 'Ulster' Imp, MPH, and Sprite, proved some of the most successful works and privateer racing cars of the late 1920s and early 1930s. At Le Mans in 1934, Rileys finished 2nd, 3rd, 5th, 6th, and 12th, winning the Rudge-Whitworth Cup, the Team Prize, two class awards, and the Ladies' Prize. Rileys also distinguished themselves at the Ulster TT, at Brooklands itself, and at smaller events like hill climbs, while providing a platform for the success of motorsports' first women racing drivers such as Kay Petre, Dorothy Champney[5] and Joan Richmond.[6][7] Another engineer and driver, Freddie Dixon, was responsible for extensive improvements to engine and chassis tuning, creating a number of 'specials' that exploited the basic Riley design still further, and contributed greatly to its success on the track.
For series production, the engine configuration was extended into a larger 12 horsepower '4', six-cylinder and even V8 versions, powering an increasingly confusing range of touring and sports cars. The soundness and longevity of the engine design is illustrated by Mike Hawthorn's early racing success after WW2 in pre-war Rileys, in particular his father's Sprite. By about 1936, however, the business had overextended, with too many models and few common parts, and the emergence of SS Cars at Coventry was a direct challenge. Disagreements between the Riley brothers about the future direction of the enterprise grew. Victor Riley had set up a new ultra-luxury concern, Autovia, to produce a V8 saloon and limousine to compete with Rolls-Royce. By contrast, Percy, however, did not favour an entry into the luxury market, and the Riley Engine Company had been renamed PR Motors to be a high-volume supplier of engines and components. The original intention of PR Motors was to produce a small car, but the outbreak of war, followed by Percy Riley's untimely death, put an end to this project.[8] The rest of the Riley companies later became part of Nuffield and then BMC, but PR Motors remained independent. After the death of Percy Riley in 1941, his business began producing transmission components. It still exists today, producing marine and off-highway vehicle applications, as PRM Newage Limited based in Aldermans Green, Coventry. Percy's widow Norah ran his business for many years, and was Britain's businesswoman of the year in 1960.
- Saloons: Adelphi, 'Continental'(Close-coupled Touring Saloon), Deauville, Falcon, Kestrel, Mentone, Merlin, Monaco, Stelvio, Victor
- Coupes: Ascot, Lincock
- Tourers: Alpine, Lynx, Gamecock
- Sports: Brooklands, Imp, MPH, Sprite
- Limousines: Edinburgh, Winchester