1948: 500 twin runs at 7:1 compression, 29bhp @ 6800rpm, 4-speed Burman CP gearbox, 6V electrics, 7” brakes, 395lb, price £217.3.6, 90mph top speed
1949: First 500s arrive in UK shops as initial production run were all exported
1950: Five-spring clutch replaces original four-spring unit
1951: Jampot rear shocks replace early candlestick-style rear suspension units
1952: Burman B52 gearbox adopted; austerity measures affect bright- and paintwork
1953: Racing kit offered with twin Amals, modified cam, high comp piston, megaphone pipes, rev counter, etc
1954: Full-width light alloy front hub; repositioned oilways in big end journals
1955: Full-width QD alloy rear wheel, another new front hub
1956: All-new frame, oil tank, toolbox; AMC clutch and gearbox replace Burman set-up. 600 models introduced with 7.5:1 compression, 33bhp @ 6800rpm, price £252
1957:…