What makes you think it's French? It looks like a good quality British 'small builder' frame from the early 50's to me, with those lugs, rear ends (Osgear style) and seat stay tops, possibly a well known one. A bit of research is called for, start here -
Agree with Ned here, early 1950's, looks like brampton cast lugs. French frame would have bottom bracket threads both right hand.
Possibly made for 26" wheels?
I would expect the chainwheel bolts to loosen.