UK, 1851, as ‘haw-doovers’—humorous and colloquial alteration of ‘hors d’oeuvres’, plural of the noun ‘hors d’oeuvre’ (i.e.: an extra dish served as a relish to whet the appetite usually before the main meal)
late 19th century—to be self-sufficient, to operate from resources accumulated earlier—refers to the ability of a camel to survive for long periods without food or water by drawing on the store of nourishment contained in its hump
UK, 1802—to go without food, or have a meagre meal, in order to save money—perhaps from the verb ‘box’, meaning: to strike with the fist, and from the male forename ‘Harry’, designating the Devil
UK, 1882—‘penny’ refers to inexpensiveness, and ‘puzzle’ to the mysterious nature of the ingredients—perhaps also in humorous allusion to ‘penny puzzle’ in the sense of a puzzle-card sold on the street for one penny