Dress dating help

[Tamzzyn]

I bought this near-mint Jon McCauley dress and I'm wondering if it is 50s or 60s, and what about the dress dates it to either decade? There is one of me wearing the dress (it's slightly too big for me in the chest area - although I could see a bullet bra looking good with it) just to show the length.

Thanks

 

[grandmascloset]

Looks late 50s early 60s.

 

[Tamzzyn]

Looks late 50s early 60s.

Thank you

 

[Circa Vintage Clothing]

Early '60s due to the soft unstructured shift shape, the keyhole back detail and the small gathers into the waistline.