Complex sentence: The project was instigated by Bill Aston, who decided to build a car for Formula Two; the chassis was a copy of the Cooper Formula Two, fitted with a flat-four engine devised by Archie Butterworth.
Split into simpler sentences: The project was instigated by Bill Aston, who decided to build a car for Formula Two. The chassis was a copy of a Formula Two Cooper, fitted with a flat-four engine devised by Archie Butterworth.