I'm guessing early sixties. 40/32 wheels, Milremo stem, the wrapover seatstay cluster, skinny stays, and cottered cranks all fit. Much later, and the wheels would probably be 36/36.
Some of the frame details match this repainted 1962 Black Diamond pretty well:
http://www.flickr.com/photos/8983160@N0 ... 356767663/
but yours is obviously a different model.
Quoting from another site:
My 62 Black Diamond frame came with a lot of Milremo parts, including hubs, stem, and bars, but did have the Dunlop steel rims and huret components, with a Williams cottered crank and Atom freewheel.
Is the top tube bent, or is that just a trick of the lens?
Calmes dans le demi-jour
Que les branches hautes font,
Pénétrons bien notre amour
De ce silence profond.