“This fine early 17th-century woman’s waistcoat is particularly significant because it is shown being worn in the Portrait of Margaret Layton (museum no. E.214-1994), attributed to Marcus Gheeraerts the Younger (1561-1636) and displayed alongside it. Waistcoats were long-sleeved upper garments, opening down the front and fitted at the waist using inserted gores. They were often made of linen and splendidly decorated as in this example. Although the waistcoat was made about 1610, the portrait was painted more than 10 years later. By this time, waistlines had risen. Margaret Layton adapted to the new style by raising her petticoat and covering the lower half of the waistcoat. V&A It’s not often we get to see a garment of such age, in good condition and with a period painting of it along side.”
– from fashionsfromistory on Tumblr. Click through to see the actual garment. It’s a very interesting comparison.