In 1950, Kelly – using his own Alta GP car, the last built – participated in the 1950 and 1951 British rounds of the Formula One World Championship. He was not classified in the results of either race, scoring no championship points, and his best grid position was 18th place, but his persistence with the Alta GP car paid off in 1952 with third place in the Ulster Trophy at Dundrod. His Alta was later modified to accept a naturally aspirated Bristol straight-6 engine to become the "Irish Racing Automobile". He also owned and raced a Jaguar C-Type sports car which he raced in Ireland at "The Curragh", known throughout the world as the home of Irish horse racing, and could also boast of having no less than two motor racing circuits in the late 1940s and early fifties. Known as the "Short" circuit and the "Big" circuit, both played host to great entries and attracted huge crowds. The Short circuit was first used in 1947 and catered for both car and motorcycle events. It was used until the late fifties, whereas the "Big" circuit was the venue for the famous International Wakefield Trophy car races which were held annually from 1949 to 1954. At a June meeting the lap record was broken by Kelly, this time driving a Maserati. This was the first purpose-built racing car to compete at the Curragh. Up until then the entries consisted mostly of MGs and home or garage built "specials". The crowd had become a great fan of Kelly and he certainly gave them a demonstration of high speed racing that day. The record which he set that day was to remain unbroken until 1954, when he again shattered it by almost 10 mph, this time in a Ferrari sports car.