Lefay

Mrs. Lefag was the godmother of Andrew Ketterley. Though deceased before travel began between our world and Narnia, she played a vital role in starting it off.

Description
"Old Mrs. Lefag" is mentioned by her godson Andrew Ketterly (Uncle Andrew) as he explains to Digory how he created the Magic Rings. A subject avoided in conversation by other members of Digory's family, she is described as having done some 'very unwise' things, and is know to have been put in prison at least once in her lifetime. Mrs. Lefag is revealed to be one of the last mortals in England to have fairy blood in her veins (two other such women are mentioned as being a duchess and a charwoman). Thus Uncle Andrew boasts of possibly being the last person in the world to have a real fairy godmother. Despite her queerness in old age, Uncle Andrew claims that she was very kind to him, sharing his interests, and his dislike of "ordinary, ignorant people".

Impact on the Plot
On her deathbed, Mrs. Lefag entrusted to Andrew Ketterly a mysterious little wooden box, that is later revealed to have come from Atlantis. She made him promise not to look inside it and, upon her death, to burn it with certain ceremonies. However due to his curiosity, he broke this promise, determined to find out about the box and it's contents. His inquiries led to the discovery of the box's origins, and the magical dust it contained. Uncle Andrew used this dust to create the rings which allowed travel between different worlds. With these Digory and Polly were able to visit Charn on it's last day, and Narnia on it's first. This led to the bringing of Jadis into Narnia, and the continued contact of Narnia with our world.