1958 Dunkley S65 scooter - the following information is from the internet.
The Dunkley S65 is a rare British scooter produced between 1957 and 1959 in Hounslow, London, known for being the first British-made OHV 4-stroke scooter, designed by Dunkley of pram fame. It features a 65cc four-stroke engine, a spine frame, and 20-inch wheels, offering a claimed 45 mph top speed and 160 mpg, marketed as a lightweight, reliable, and "sporty" commuter.
The S65 is powered by a 65 c.c. OHV oversquare 4-stroke engine with a 2.6 b.h.p. output at 5,200 rpm. It utilizes a 2-speed gearbox, with comfortable cruising speeds reported between 22–35 mph.