According to Brady (Clavis Calendaria), this designation arose from the fact that in an old romance a prince of the name of Crispin is made to exercise, in honour of his namesake, Saint Crispin, the trade of shoemaking. There is a tradition that King Edward IV., in one of his disguises, once drank with a party of shoemakers, and pledged them. The story is alluded to in the old play of George a-Greene (1599):
Marry, because you have drank with the King, And the King hath so graciously pledged you, You shall no more be called shoemakers; But you and yours, to the worlds end, Shall be called the trade of the gentle craft.