In 1911 the company diversified into motorcycle production. The first motorcycle to be manufactured was a single-cylinder F-head, 500 cc bike. Rudge-Whitworth also produced the first detachable wire wheel and became known for its innovations in engine and transmission designs and its racing successes.
In 1935 the company was taken over by EMI. The business was moved to Hayes, Middlesex four years later and ceased to manufacture motorcycles. EMI soon decided that cycles were not for them and Rudge-Whitworth was sold on to Raleigh in 1943.
I have only seen the Rudge-Whitworth overprint on SG 421 as shown.
by Mark Matlach