Amazing vintage cocktail dress! Taffeta with a petticoat. Probably from 50s

This is an amazing find. Purchased in London in the 80s it’s a 1950s? Cocktail dress in black taffeta. With a petticoat and a side zipper. It runs small around bust and waist. The label says The Linzi Line Made in England. They made cocktail dresses in the 50s. I wore this to a black tie ball at Oxford Univ in 1987. Vintage. Very good condition. No rips or tears. Needs a major dry clean and some stitching at the strap.