Although BSA were latecomers to the motorcycle market, they did not make their first complete machine until 1910, they soon became a market leader. Vast numbers of good reliable motorcycles left their Birmingham factory in ever-increasing numbers and with such an extensive range of models there was something to meet almost every requirement. Their familiar slogan 'The most popular motorcycle in the world' was widely recognised, so much so that letters from overseas bearing only this slogan were invariably delivered to Armoury Road in Small Heath. The company began making vee twins in 1920, but it was not until the early post-World War 2 period that vertical twins became a key feature of their model range. If everything had gone according to plan, they expected to launch two such models at the 1940 Motor Cycle Show. Well aware of the potential of Edward Turner's Speed Twin Triumph which broke new ground in 1937, they lost little time in producing prototype designs that would match the Triumph, and had them running in 1939. Sadly, World War 2 curtailed further development and when the production of civilian models resumed after the war, two entirely new models had taken their place. The first was a 495cc vertical twin designed by Herbert Perkins, the A7 model. It was subsequently redesigned in 1949, after Bert Hopwood had joined BSA as Forward Product Designer. Hopwood also took the opportunity to introduce a 646cc variant in 1950, the renowned A10 Golden Flash model, which became BSA's most popular twin in the fifties. It is these models and their later variants with which this book concerns itself, all of which have a separate engine and gearbox. Many memorable feats have been accomplished by BSA twins, but none more so than their Maudes Trophy attempt in 1952. An A.C.U. Certified Test, it began when an A.C.U. official selected three 497cc Star Twins from the production line and had them sealed and locked up until the test commenced. Three BSA works riders then rode them from Birmingham to Oslo, competing on the way in the gruelling International Six Days Trial held that year in Austria. All three machines covered 4,958 miles in 24 days and completed the trial without losing a single mark, to make it one of the most outstanding feats of all time for standard production models. BSA were awarded the Maudes Trophy for the first time since 1939 and all three riders a Gold Medal from the trial. Sixty international articles cover the Twins A7 & A10. This is a book of contemporary road, comparison & race tests, history, performance & technical data, engine analysis & rebuild. Models covered: Road Rocket, Golden Flash, Super Rocket, Gold Star, Star Twin & Shooting Star. 172 pages, 300+ illus. SB.