Meet Aunt Sempronia. She is the great-aunt of protagonist Charmain Baker in House of Many Ways, and begins all the action by arriving at the home of her nephew-by-marriage (Charmain's father Mr. Baker) to announce that someone needs to look after the home of her great-uncle William (Wizard Norland). She further explains that she herself is far too busy to do it, what with her many charities. Charmain's mother counters with how busy they are at the bakery, what with all the wedding cake orders that month.
"Then it has to be Charmain," Great-aunt Sempronia announces firmly, and of course it does -- Charmain goes off in Great-Aunt Sempronia's pony cart to begin the greatest adventure of her life.
Great-Aunt Sempronia arrives later in the novel, on a visit with Charmain's mother, the respectable Mrs. Baker. Thanks to quick thinking on Charmain's part, this visit doesn't go too badly, and Charmain is able to keep quite a few embarrassing things from her mother's sight. After the two ladies have had morning coffee (magically produced by the magic trolley) and some conversation, they sweep back out of the house again, leaving Charmain very relieved and the wizard's house ready for the next few adventures.