To protect themselves, bakers would add a small piece of bread to each order, called the "in-bread", to ensure they could not be accused of short measure.
In years of good harvest, a baker could be making more bread than could be sold from the shop.
Extra bread was then sold on to middlemen or "hucksters", who would resell it in the streets.
Since the price of bread was fixed by law (again by the Assize of Bread and Ale), this was advantageous for both parties: the baker would manage to sell the surplus bread to the huckster, and the huckster would in turn make a profit by selling the vantage loaf, the 13th loaf gotten free.
Vantage of bread; the thirteenth loafe given by Bakers unto the dozen.This bread-related article is a stub.