Brand new with tags.

AU/UK 12, but since it is vintage it will probably fit a size S or M. See measurements below. 

Measurements: 

Armpit to armpit: 14 inches (unstretched) --> 17 inches (stretched)

Waist: 11 inches (unstretched) --> 14 inches (stretched)

Length: 24 inches

All measurements taken with the garment lying flat.

Elastic is still great.

Has a low back, underwire, and ruching for a great slimming effect.