Despite only building its first car in 1961, by the mid-1960s MRD had overtaken established constructors like Cooper to become the largest manufacturer of single-seat racing cars in the world, and by 1970 had built over 500 cars. Of the other Formula One teams which used Brabhams, Frank Williams Racing Cars and the Rob Walker Racing Team were the most successful. The 1965 British Grand Prix saw seven Brabhams compete, only two of them from the works team, and there were usually four or five at championship Grands Prix throughout that season. The firm built scores of cars for the lower formulae each year, peaking with 89 cars in 1966. Brabham had the reputation of providing customers with cars of a standard equal to those used by the works team, which worked "out of the box". The company provided a high degree of support to its customers—including Jack Brabham helping customers set up their cars. During this period the cars were usually known as "Repco Brabhams", not because of the Repco engines used in Formula One between 1966 and 1968, but because of a smaller-scale sponsorship deal through which the Australian company had been providing parts to Jack Brabham since his Cooper days.