In 1974, Postlethwaite designed an all-new car for the team, the Hesketh 308, which was ready for the Silverstone International Trophy, which Hunt won, making its championship debut at the South African Grand Prix. The car was strong, taking third place at the Swedish Grand Prix, the Austrian Grand Prix and the United States Grand Prix. For 1975, examples of the 308 were sold to Harry Stiller Racing, who gave Alan Jones his grand prix debut. Polar Caravans also purchased a Hesketh chassis, while the works team modified the 308 for Hunt. At the same time, Horsley was developing into an efficient and competent team manager and under his guidance, the team moved forward.