I can assure you that no one would have bought this in 1965. Or 1975 either. Or any decade I have lived through.
It's such a shame - one of my wardrobe staples is a plain black, knee length, v neck, sweater dress, 50% wool and 50% acrylic. It has a St Michael label. Every time I wear it people say what a great dress. That was what M&S used to sell.