Excellent pre-owned condition. I do not think this was worn often, if at all.  There are two small snags near the hem in the front, in the  overlay layer of the nightgown. There is a small snag and a very small stain on the outside of the inner gown. 

Shoulder to hem is 51 inches.  45 seam to seam sweep. 28 inches pit to pit/chest, 24 inch waist, empire style.

Marked as a 34, I believe this is a small.

After doing some digging online and reviewing Vanity Fair's label history, I do think this was likely produced in the 1950s.