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Walter Owen Bentley (September 16, 1888 – August 3, 1971), often known as W. O. Bentley or just "W. O." was the founder of Bentley Motors.
1888 Born on 16 September 1888 at 78 Avenue Road, Hampstead, London, the youngest in the family of six sons and three daughters of Alfred Bentley, a merchant in silks and woollens, and his wife, Emily Waterhouse.
1911 Living at 80 Avenue Road, Hampstead: Alfred Bentley (age 69 born London), Private means. With his wife Emily Bentley (age 57 born Adelaide, Australia - British subject) and their six children; Clara Bentley (age 35 born 36 St. John's Wood Park); Hilda Bentley (age 28 born 36 St. John's Wood Park); Leonard Well Bentley (age 27 born 36 St. John's Wood Park); Arthur Waterhouse Bentley (age 26 born 78 Avenue Road, Hampstead), Surveyor; Horace Milner Bentley (age 25 born Summerfield, Hampstead Heath), Chartered Accountant; and Walter Owen Bentley (age 22 born 78 Avenue Road, Hampstead), Engineer, Motor Cab Company. Three servants.
After leaving Clifton College at sixteen and a premium apprenticeship (1905–10) with the Great Northern Railway at Doncaster, he raced motorcycles and cars, and worked as a driver and mechanic for the National Motor Cab Company.
In 1912 he joined his brother, Horace Millner Bentley, in a company called Bentley and Bentley selling French DFP cars. Unsatisfied with their performance, W. O. designed new aluminium alloy pistons and a tuned camshaft for the DFP engine, taking several records at Brooklands in 1913 and 1914.
1914 Married Leonie Gore at Hampstead. 
During World War I, he was a Captain in the Royal Naval Air Service, where he played a major role in improving the design and manufacture of Clerget engines for the Sopwith Camel and the Sopwith Snipe aircraft. These were known as the BR1 (Bentley Rotary 1) and BR2 and were made by Humber. For this he was awarded an MBE, and an award of £8,000 from the Commission for Awards to Inventors.
1920 Married (secondly) Audrey Hutchinson. 
1920 After the war, he founded his own motor car company, Bentley Motors. W. O. designed a high-tech four-cylinder engine and sturdy chassis, the Bentley 3 Litre. Its durability earned widespread acclaim. The 3 Litre won the 24 hours of Le Mans in 1924 and following models repeated this each year from 1927 through 1930. His racing manager was an old school friend, Richard Sidney Witchell. Bentley set many records at Le Mans: "Bentley Boy" Woolf Barnato was the only driver to win on all three times he entered, giving him the highest victory percentage.
Bentley's racing success failed to keep the motor car company afloat, and W. O. was forced to sell a majority share to raise cash. The "Bentley Boys" came up with the money, with Woolf Barnato, heir to Kimberley diamond magnate Barney Barnato, becoming the majority shareholder. W.O. stayed on to design another generation of cars, the six-cylinder 6½ Litre, but his control was slipping. Against his wishes, Barnato allowed the supercharged "Blower" version of his 4½ Litre car to be built, but durability was poor and the car failed on the track.
The Wall Street Crash affected Bentley's business greatly, especially as the company had just launched the 8-Litre as a grand car for the ultra-rich. After unsuccessful attempts to save the company, Barnato and Bentley were forced to sell to an anonymous holding company, British Central Equitable Trust, in 1931. This turned out to be arch rival Rolls-Royce, who had been disturbed by the 8 Litre's encroaching on the market turf of their Phantom II.
W.O. remained with the company until 1935, working on the 3½ Litre and other models. But Rolls-Royce closed the racing department, and Bentley eventually decided to go.
Bentley moved with the majority of the racing department staff to Lagonda, which was recently saved from receivership by Alan Good. There, Bentley again went racing, and his Lagonda MG45 Rapide, won Le Mans in 1935. His 4,480 cc V12 engine was a masterpiece of engineering, developing 180 hp (134 kW).
After World War II, Lagonda was bought by David Brown, who combined it with Aston Martin. Brown had purchased Lagonda largely to gain Bentley's engineering expertise, and immediately placed his 2.6 L straight-6 engine under the bonnet of his DB2. This durable DOHC engine would continue in use at Aston through 1959. Bentley remained as an engineer at Aston Martin for a time, moving to Armstrong Siddeley Motors where he designed a twin overhead cam 3 litre engine before retiring.
W. O. married three times, first to Leonie who died in 1919, then to Poppy and finally in 1934 to Margaret. He had no children. Bentley died in 1971 as a revered patron of the Bentley Drivers' Club. His widow Margaret lived until 1989.
1971 Obituary 
Walter Owen Bentley, MBE (Fellow) of Guildford died on Aug 13. Born in 1888, he first became a premium apprentice at the Great Northern locomotive works at Doncaster.
Those apprenticeship days taught him the highest standard of workmanship, which was the hall-mark of his every creation.
After completing his apprenticeship he found that the locomotive, was likely to provide a restricted future, and almost reluctantly turned to the internal-combustion engine, first with two-wheeled vehicles, when tuning his Rex and Indian motor cycles, then graduating to four wheels, and 1910 saw him maintaining some 250 Unic Taxi cabs of the National Motor Cab Co.
In 1912, his brother joined him and together they acquired the British agency then distributing the French DFP car. During the next two years, he modified this staid family conveyance into a competition model, which invariably made fastest time in its class in any event in which he could participate, astounding the manufacturers, whom he persuaded to make up special pistons to his own specification, comprising mainly aluminium, a then entirely new metal for such a component.
In 1914, he became a lieutenant in the RNAS, where he introduced his aluminium piston to the aircraft manufacturers for fitting to their engines. Service with squadrons near the front showed him the necessity for the utmost reliability needed in the air, and it was not long before the first Bentley Rotary engines were being produced, the BR1, one of the most successful of Britain's first world war fighter aircraft units, and the later BR2 for which an order for 30 000 existed before hostilities ceased. With the return of peace, though order books were full, selling DFPs seemed a limited field for a talented designer, and by 1919 his first car engine, the 3-litre Bentley had appeared.
Bentley's company was taken-over by Rolls-Royce Ltd in 1931 and in 1933 a new form of Bentley emerged, but not of his design. Shortly after, he joined Lagonda's to improve their existing 4.5-litre model, and to evolve the latest Bentley design, a V12 Lagonda. Later came the new twin overhead camshaft 2.5-litre Lagonda, with independent suspension all round, which was subsequently fitted into the Aston-Martin.
W. O. Bentley enjoyed over 40 years of brilliant design and achievement. Always striving for mechanical perfection, his enthusiasm was aptly expressed in his autobiography (published by Hutchinson), when at the age of 69 he said, 'the world of high-performance cars is an especially tough one, and I should think it is going to be even tougher in the future. But, given the energy and ambition I had in 1919, in the context of 1957, I think I should have another go ... '