I'm gonna say circa 1960, but five years either way would be quite possible. Much later, and you start to see more plastic in the fittings, and the vogue goes from curves to straight lines.
Lots of lovely, idiosyncratic French features - the LeFol Martelé mudguards, guidonnet levers, racks that double as mudguard stays (or mudguard stays that double as racks), that kitschy chainguard, and the demi-ballon (650B) tyres. Four-speed freewheel?
You still see quite a lot of this type of bike in use in France. If you want to see one in its native setting, watch "Les Parapluies de Cherbourg" - a French musical of the mid sixties set a few years earlier. Guy, the protagonist, a garage mechanic, rides something quite similar.