I think late 50s/early 60s, and soutache is the term I'd use for the trim. By cotton linen, do you mean a cotton-linen blend? Can you show a swatch in a closer-up close-up? It does look like linen "from here," but it could be a heavily slubbed raw silk or a number of weaves of cotton. Or a blend of any two of those fibers. Is it soft and supple or crisp and sort of stiff? Is there a seam on the inside you can snip a bit of and do a burn test if the look and feel aren't conclusive?
I think it's darling.