1475, Flanders - Ghent
MS. Douce 365: Moral and religious treatises,
fol. 115r - Margaret of York at prayer
Margaret and the other lady closer to her wear later 15th century variants of the fitted gown, derived from the houppelande, and a black hood or frontlet with steeple hennin. The fitted silhouette of the gown is accentuated by the wide belt, worn so tight around the waist it almost seems to merge with the dress.
(For an even later example of the houppelande’s evolution, although English, see this beautiful funerary brass. The only conspicuous vestigial part of the dress that is referencing its predecessor (the houppelande) is the overturned collar/lapels.The belt is narrow and worn low, reduced to a decorative function - the dress is presumably fastened with hidden lacing in the front. Technically, the gown has become an overkirtle.)
The third kneeling lady wears an overkirtle with wide opening in the front, held together with horizontal lacing. Underneath a kirtle would be worn and also maybe an embellished stomacher (also known as a placket). The bust seems flattened and the torso straight - the inclination towards this kind of silhouette foreshadows the imminent advent of the corset.
(Several similar examples (all by Memling): 1470s detail of kneeling daughter of a donor from Donni triptych, 1480 detail of Mary Magdalene from Adriaan Reins triptych, 1485-90 lady with a pink)