Nanny Plum is the teacher to Princess Holly and her sisters, Daisy and Poppy, and she serves as the general housekeeper to King and Queen Thistle. She is eccentric, and this eccentricity is what makes her appealing to the viewing audience. She is an experienced magic user and learnt magic at the facility of Mrs Fig. She is kind to Holly and her friends and family, and her employers, but when Cedric Elf is in the vicinity, they often fight over pointless subjects such as how to properly bake cakes. Nanny is portrayed chiefly as an authority figure, but does not act like one. She has gotten lost in space, and has headed an expedition to various places in the Little Kingdom for King Thistle's medicine, that Nanny proposed, and preceded to create later on in her cauldron.
Nanny is the occupant of several jobs for the royals, including motorcar driver, and proprietor of the library that is located inside the Little Castle. She handles the teaching of the nature class that is attended by the faries. She often spearheads any insults to Cedric Elf, and is known to have a love-hate relationship with him. She is known for her loyalty to her chief employer, King Thistle. She has a good relationship with the aliens who govern and inhabit Planet Bong. She is finally known for her good relationship with Holly's friend Ben Elf, and they have called on each other several times when they have gotten into accidents and emergencies.