Who is Gytha (Nanny) Ogg from Lords and Ladies: A Novel of Discworld and what is their importance?

Nanny Ogg is a witch..... the second oldest witch in Lancre. She is also the maternal leader of the Ogg family. Nanny is described as fun-loving, chubby, and passionate. Unlike Esme, Nanny Ogg is easygoing..... her main concern is ultimately the menu.