A holiday observed by journeyman shoemakers and other inferior mechanics, and well-to-do merchants.
In the Journal of the Folk-lore Society, vol. i. p. 245, we read that, “While Cromwell's army lay encamped at Perth, one of his zealous partisans, named Monday, died, and Cromwell offered a reward for the best lines on his death. A shoemaker of Perth brought the following, which so pleased Cromwell that he not only gave the promised reward, but made also a decree that shoemakers should be allowed to make Monday a standing holiday.”
Blessed be the Sabbath Day, And cursed be worldly pelf: Tuesday will begin the week, Since Monday's hanged himself.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894