Guinness was a racing driver, and hired his brother, Kenelm, as his mechanic. He funded his motor racing with his inheritance from the
Guinness family, competing in his first speed trials in
Portmarnock in 1904 and later participating in th
Gaillon hill climb in France, reaching a record speed of 89 mph. He completed the
Ostend speed trials, reaching a top speed of 117 mph, in 1906. Later that year, Guinness purchased an 18-litre V8 Darracq, and used it in his
Brooklands race in September, reaching a speed of 115 mph. He placed third in the
Isle of Man Tourist Trophy in 1907 and placed second and third in two circuit races in
Ardennes. Guinness crashed through a barrier during the 1908 Isle of Man Tourist Trophy after failing to make a turn while going 80 mph, killing a spectator. He served in the
Royal Naval Volunteer Reserve during
World War I as an acting
lieutenant commander, from 1914 to 1918. Like his parents, he was fond of sailing and yachting, and raced a high-speed boat in the 1920 British International Trophy for the
Harmsworth Cup, but lost to the American racer
Garfield Wood. He returned to motor racing and, in 1922, he won the Isle of Man Tourist Trophy for
voiturettes, reaching an average speed of 53 mph over a distance of 226 miles. Following his retirement from racing, Guinness served as a steward of the
British Racing Drivers' Club and the
Royal Automobile Club. He again served during
World War II, this time as a
flight lieutenant in the
Royal Air Force Volunteer Reserve, where he was involved in air-sea rescues. == Personal life ==