The first known scramble race took place at Camberley, Surrey in 1924. During the 1930s the sport grew in popularity, especially in Britain where teams from the Birmingham Small Arms Company (BSA), Norton, Matchless, Rudge, and AJS competed in the events. Off-road bikes from that era differed little from those used on the street. The intense competition over rugged terrain led to technical improvements in motorcycles. Rigid frames gave way to suspensions by the early 1930s, and swinging fork rear suspension appeared by the early 1950s, several years before manufacturers incorporated it in the majority of production street bikes. The period after World War II was dominated by BSA, which had become the largest motorcycle company in the world. BSA riders dominated international competitions throughout the 1940s.