First introduced in 1926, Percy Riley's 9hp, 1,087cc, twin-camshaft four was an outstanding engine design by any standards, various versions powering Rileys until 1957.

Looking to all intents and purposes like a twin-overhead-camshaft design, the Nine's cross-flow cylinder head featured hemispherical combustion chambers and valves inclined at an included angle of 90 degrees.

The twin gear-driven camshafts were mounted high in the block, operating the valves via short pushrods.

Right from the start it was obvious that the 9hp Riley engine possessed enormous potential as a competition unit and at Brooklands J G Parry-Thomas and Reid Railton were the first to demonstrate just how good it was.

The success of their racer led to a production version, the Speed Model, which soon became known as the Brooklands Nine.

Numerous World Speed Records and famous class victories at Brooklands, Shelsley Walsh, RAC Tourist Trophy and Le Mans followed, while outright wins were secured at the Ulster ...