The Birmingham Small Arms Company (BSA) in the United Kingdom began manufacturing firearms before diversifying into the manufacture of bicycle components during the 1880s. By 1900, the firm was a leading supplier of bicycle components and many Australian-built bikes incorporated BSA parts. BSA began producing motor cycles in 1906. Early motorcycles such as this example were single-cylinder designs but V-twins were introduced from 1921 and by the late 1920s the company was also making two-stroke machines. The Gold Star model released in 1938 was made in trial, scramble, touring and racing versions and was the company's most successful design.
During the Second World War, BSA was the largest UK supplier of motorcycles to British and Commonwealth forces with the M20 model. Once Britain's largest motorcycle manufacturer, BSA stopped producing their own motorcycles in the early 1970s. Finlay Brothers Motor Cycles was the local BSA agency in the 1920s and 1930s, located at 322-324 Elizabeth Street. Before this the sole Victorian agent was Milledge Bros. located at Post Office Place, Melbourne. The BSA Models H and K were fitted with the same single-cylinder 4.5 horsepower engine of 557cc capacity. These models were widely used during the First World War by British and Australian military despatch riders. An optional 'BSA Sidecar Model No. 2' could be fitted to carry a passenger.