Son of a well to do London business man, Walter Owen Bentley started his career as a railway apprentice. His hobbies included cricket and motorcycle racing. In 1910 he bought his first car a Riley V-twin two-seater. Completing his apprenticeship Mr. Bentley worked as a general assistant for the National Motor Cab Company in Hammersmith. In 1912 he joined his brother(H.M. Bentley) in selling French DFP cars.

The DFP cars were not very fast and the Bentley brothers were able to improve performance by using lighter pistons made of 12% copper and 88% aluminium. This allowed the French DFP cars to achieve a top speed of 89.7 mph (quite a respectable figure for a two liter engine), they convinced the French automakers to institute the changes on the production model which was marketed as the 12/40, however the production was cut short due to the outbreak of World War I.

Working for the Technical Board of the Royal Naval Air Service during the war Bentley's experience with aluminium pistons proved invaluable in improving the French Clerget rotary engines and the modified designs bore his name (the Bentley Rotary 1 & 2).

After the war Walter returned to partnership with his brother, but his dream was to produce a car bearing his own name. In 1919 he left the partnership to found Bentley Motors Ltd. the successor to he and his brother's partnership which had been primarily a sales organization. The company was underfunded from the beginning and a mortgage had to be taken out to finance the construction of a factory in Northwest London, although the prototypes were not built there. The first prototypes were constructed in a factory owned by J.H. Easter who did the body trimming on the DFP's. Bentley made a partnership with Frank Burgess who had been vital in the development of the twin overhead cam engine for Humber, used in that company's 1914 Touring Trophy racing cars.

Burgess brought a TT Humber to Bentley Motors and some of the Humber designs are reflected in the First Bentleys, however the engine only had a single camshaft. There were 4 valves per cylinder with dimensions of 80 by 149 mm,a long stroke even for those days. The engine capacity was just under 3 liters in volume and it was christened the 3 liter model. This was the first time a British car was described in liters which puzzled motorists who were used to hearing about engines in terms of horsepower, however with a RAC rating of 15.9 horsepower would have made the engine seem small and not taken into account the Bentley's unusually long engine stroke. The rest of the car was pretty much standard for the day. The car was announced in 1919, the description being accompanied by a drawing because an actual production model had yet to be completed. At London's first autoshow after the war Bentley displayed a non-running chassis, promising deliveries of a working model by June 1920 but development took longer than expected and the first models were not delivered until fall of 1921. The car was a two-door saloon style and customers paid 1150 pounds (the quoted price in 1920 was 750 pounds) for the chassis. The cars more than lived up to the original promises and customers had to wait two years on a waiting list before receiving their models. 21 were delivered in 1921, peaking at 408 in 1928.

Victories on the speedway and celebrity owners were vital to the success of Bentley in these early days and there was no shortage of either. Not having their own coachworks Bentley recommended standard bodies, the open 4-seat touring bodies were maid primarily by Vanden Plas, who had a shop close by. Other coachbuilders were asked to work on the 3 liter, and many styles would be seen over the years. However the demand for closed coachwork made Bentley realized that a more powerful engine would be needed. He first conceived a 6 cylinder 3-liter, but a fortunate run-in with the first prototype Rolls-Royce Phantom made him realize that a larger engine would be needed. The six cylinder devised by Bentley for his new line had a capacity of just over 6.5 liters.

This new model included many new design features including four-wheel brakes, a heavier differential and a camshaft drive that had a three - throw coupled rod rather than the vertical shaft of the smaller model. In 1928 a sporting version was released known as the "Speed Six", the Speed Six was probably the most successful racing Bentley achieving two consecutive victories at LeMans.

Bentley firmly believed that there was no replacement for liters and would rather enlarge the engine than supercharge a smaller one. The 8 liter Bentley couldn't have been released at a worse time, hitting the market in 1930 the depression was having a particularly bad effect on the expensive car market. Only 67 of the 8 liter Bently's were sold by the company while it was still independent.

Bentley Motors was seriously underfunded and probably would have collapsed if not for the intervention of Woolf Barnato in what was effectively a takeover. However Barnato's fortune had been seriously hit by the depression and he was not able to support the Motor company for long. It was expected that Napier would aquire Bentley especially as W.O. Bentley had been in discussions with the company about producing a new twin overhead cam sportscar. However Napier was outbid by the mysterious British Equitable Trust Ltd. (Bentley would find out later at a cocktail party that this new firm had been acting on behalf of Rolls-Royce).

Rolls-Royce kept W.O. Bentley on as an employee and created Bentley Motors Ltd. as a wholly owned subsidiary of Rolls-Royce. Bentley however, had little to do in the design of the future cars that would bear his name and he left when his contract came up for renewal in 1935. He joined Lagonda where he designed the LG6 and V12, he also designed the 2 1/2 liter twin-overhead cam engine which was used in post WWII Aston Martin DB2s. W.O. Bentley died in 1971.

Rolls Royce however has continued to make cars using the Bentley name to this day. Bentley cars are still looked upon as some of the finest in Britain.