he emptied the palace privies , delivered its sparse mail , guarded the walls , operated the royal mint , balanced the budget , helped out the gardener in his spare time and , on those occasions these days when it was felt necessary to man the borders , and verence felt that yellow and black striped poles did give a country such a professional look , he stamped passports , or at a pinch any other pieces of paper the visitor could produce , such as the back of an envelope , with a stamp he 'd carved quite nicely out of half a potato .