If you are interesting in getting an inside view of what happened to Norton a book worth reading is >Whatever Happened to the British Motorcycle Industry< by Bert Hopwood. http://www.amazon.com/Whatever-Happened ... ewpoints=1
He was involved with Ariel, BSA, Norton and Triumph as both an engineer and company director from the fourties until the demise of the British Bike industry.
As a design engineer he advocated for developing the next generation of motorcycles but was resisted by a penny pinching Board of Directors that should have been running a company building washing machines.
Their attitude was anyone wanting a serious motorcycle would buy British so why not just keep cranking out the same old design.
Totally not willing to recognize the threat from the Japanese. Japanes bikes had starters, didn't leak oil or need regular owner tweaking.