Endless Wrench is the source where I discovered this. There is also some text, it goes thus:
"1936 Rudge Speedway Factory Racer from British Rudge Motorcycle
Manufacturing Company LTD. It was owned and raced throughout California
in the 1960s by Sonny Kenyon. It is all original and unrestored.
Powered by a 4 stroke 500cc single cylinder J.A.P. with ethanol burning
and 4 VALVE HEAD!!!"