Motocross is a form of off-road motorcycle racing held on enclosed off-road circuits. The sport evolved from motorcycle trials competitions held in the United Kingdom. Motocross first evolved in Britain from motorcycle trials competitions, such as the Auto-Cycle Clubs's first quarterly trial in 1909 and the Scottish Six Days Trial that began in 1912. When organisers dispensed with delicate balancing and strict scoring of trials in favour of a race to become the fastest rider to the finish, the activity became known as 'hare scrambles', said to have originated in the phrase, 'a rare old scramble' describing one such early race. Though known as scrambles racing in the United Kingdom, the sport grew in popularity and the competitions became known internationally as 'motocross racing', by combining the French word for motorcycle, motocyclette, or moto for short, into a portmanteau with 'cross country'. 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.