Polka dot patterned jacket from the UK (size Medium)

Bought this jacket in London 20 years ago, even though it didn't fit me because it's that adorable--just wanted to own something this cute. It's missing two buttons and has staining on the left elbow (see pictures). Not sure what material it's made from but it's basically wrinkle proof. Armpit to armpit: 15 inches Length (from shoulder to hem): 33 inches Bottom hem: 22 inches Waist: 15.5 inches Measurements taken with garment laying flat