Cerys Banda was the last queen until Jenna, her daughter became the queen.
She is the wife of Milo Banda, who lived and was born in the Far Countries. Cerys Banda was a good queen. On the longest night, she gave birth to a baby. That night, Alther, the ExtraOrdinary Wizard and Marcia, his Apprentice, were with Cerys in the Throne Room. An Assasin came and shot Queen Cerys and Alther, but Marcia and the baby escaped.
She would not appear to anyone, not even to her own daughter, Jenna. She says that she will when the Time is Right.
She appears in the ending of the second book, listening to the conversation between her husband and daughter; the third book, where she approves of Septimus being a friend of Jenna; and the 5th book, talking to Aunt Zelda and confirming that Wolf Boy shall be the Intended Keeper of Keeper's Cottage.