A vision of what might have been - this derailleur would have been a killer product in 1965 (when Simplex had all the ingredients in place to make it). Unfortunately it took Simplex another two decades to shrug off their obsession with plastics and make this gear - effectively an affordable metal ‘Prestige’. By that time it was only of interest to industrial archaeologists.
I like the logo incorporating the outline of France. I am interested by the funky sculpting of the pulley cage plates - presumably to improve the gear change. And I am amazed by the way they have managed to finish a competent product so that it appears cheap and undesirable.