The New York Times ran a story about her, possibly wearing this dress and footwear. She world have been very much in her element in the 1960s.
From the USA Library of Congress Bain collection.
The Baroness wears a figure-revealing tight columnar dress with a train in this 1913 photo. Her sleeves are barely visible.
Keywords: 1913, Baroness de Guestre, Baroness, French, straight coiffure, hair jewelry, under-bodice, long flared sleeves, no waistline, maxi-length skirt, over-bodice, strap sleeves, over-skirt, angled hemline, train, necklace, earrings, sandals