Edgar Westbury's 10cc Ensign 2 Stroke rear valve engine-first published 1955 & found during a clearout of my late father in laws shed.
Plus Stefan Gasparins G24 CO2 motor.
Info on the great Edgar T Westbury here
http://modelenginenews.org/etw/index.html
Currently having a clearout & wanted to have some record before it all goes- I just love the crankcase fins on the big un & it turns over
with a beautiful "thwack" !