The Wikipedia article for “Margaret and mary Shelton” has this portrait and suggests they may be the same person (without benefit of quantum physics). She may have been six-months lover to Henry VIII in 1535 (while he was married to Anne Boleyn to whom Lady Mary was a Lady-in Waiting). She was married to Sir Anthony Heveningham.
From Wikimedia. Originally found on pinterest.com/crownedheads/1500-gabled-head-dress/.
Holbein again portrays an English Lady wearing a gabled English hood and a simple dress with crescent neckline. Her bodice has rever-like strips and a contrasting center stomacher section.
Keywords: Holbein - Hans the Younger, Lady Mary Heveninham Shelton family, Heveninham family, English, mistress, Henry VIII, Lady-in-Waiting, Anne Boleyn, English hood, bodice, crescent neckline, revers, stomacher, close upper sleeves, full middle sleeves, necklace, pendant, brooch