Vintage Valentino houndstooth slim skirt. Size 12/ fits like 10

This vintage Valentino skirt is classic style. Circa 1980 ( perhaps as early as 70s) and is in great vintage condition. It is a vintage piece & the label reads size 12 but it fits more like a modern day size 10. I could not find the original price for this piece so the original price reflects what a modern skirt in the same styling cost currently at valentino.