From what you've said Jenny it sounds very much in the late 1940s-1950's category. I would be inclined to say 1950s because of that luxurious metallic fabric and the dimante buttons. Those wide turned up cuffs on the sleeves and the peplum were popular in both decades on womenswear. If you can show the shoulder pads and they are the original ones, we may be able to narrow the date down further by their size and shape.
If you are unsure of the decade by looking at the item, something I will sometimes look at is the ratio of measurements taken across the garment for bust, waist and hips. The difference between the bust & waist is generally more extreme is the 40s/50s than the late 60s to 70s. I find particularly 70s is a very slim shape overall with a small chest and long.