The Magicians of Caprona

Blurb

The Magicians of Caprona is a children's fantasy novel by British author Diana Wynne Jones published by MacMillan Children's Books in 1980. It was the second published of seven Chrestomanci books.
It features the venerable Italian family spell-houses Casa Montana and Casa Petrocchi in Caprona, a small independent city-state and duchy.
The Chrestomanci books are collectively named for a powerful enchanter and British government official in a world parallel to ours, who supervises the use of magic —or the Chrestomanci, an office that requires a powerful enchanter and is responsible for supervising. The Magicians of Caprona is set in our time, during the tenure of Christopher Chant, who is Chrestomanci in five of the seven books and is often called Chrestomanci as a personal name.