The BSA Golden Flash, commonly referred to as the Gold Flash,[4] was a 646 cc (39.4 cu in) air-cooled parallel twin motorcycle designed by Bert Hopwood and produced by Birmingham Small Arms Company (BSA) at Small Heath, Birmingham.

In May 1948, the factory enticed Hopwood after only a year at Norton,[6] and he was commissioned to create a competitive BSA parallel-twin.

[7][8] Launched in October 1949, Hopwood's A10 Golden Flash drew heavily from the A7 design by Page and Bert Perkins.

[9] The A10 was increased to 650 cc (40 cu in), with a revised alloy rocker box and cast-iron cylinder head, plus an integral manifold for the single Amal carburettor.

The frame was available in rear rigid format, but the more common option was plunger suspension, adopted for the export market.

The A10 was so closely based on the A7 that it used many of its well-proven components, and this large carry-over of parts from the A7 promised greater reliability, with minimal risk of new technical problems.

[9] The BSA Golden Flash was launched in a new gold colour, and 80% of production was destined for the United States.