- "Get out of my house this moment, you shameless hussy, or I'll send for the police."
- ―Letitia Ketterley to Queen Jadis [src]
Letitia Ketterley (or Aunt Letty) was Digory Kirke's aunt, the sister of his uncle Andrew Ketterley and his mother Mabel Kirke. She was unmarried, and resided in a house in London with her brother and a housemaid named Sarah. Digory and his mother stayed at the house while his mother was ill.
Described as "a very tough old lady" with a "firm quiet voice", Letitia was likely was the first person other than Digory, Polly Plummer and Andrew to see Jadis when she arrived from the World of Charn.
Despite Jadis' fearsome appearance and extreme temper, Letitia was not intimidated in the least. Thinking she had come from a circus, and disapproving of her bare arms, Letitia immediately ordered Jadis to leave or she would inform the police.
When the witch tried to cast a spell and realized that her magic had no effect on Earth, Letitia further dismissed her as a drunk (mistaking the incantation for ordinary English). In anger, Jadis grabbed hold of Letitia and threw her across the room, though luckily she landed on a mattress that she had been mending.
After Jadis left the house with Andrew and Letitia had recovered from the shock (which took only a few minutes), she ordered Sarah the housemaid to go to the police station and warn them that a "dangerous lunatic" was out on the streets.
After Mable had recovered from her illness and was enjoying fun and games with Diggory and Polly, Letitia affectionately declared that she was "the biggest child of the three."
Despite her tough exterior, Letitia was a clearly a loving person: She was very distressed over the declining health of Digory's mother,  and when Mrs. Kirke miraculously recovered (thanks to the silver apple that Digory brought back from Narnia), Letitia did everything she could to make her happy.
Letitia's relationship with her brother Andrew was not as amicable. While the specifics were unclear, Andrew's extravagant spending and lack of regular income over a thirty-year period had forced Letitia to cover his expenses repeatedly.