Which C.S. Lewis novel introduces the character Digory Kirke as a child?

The C.S. Lewis novel that introduces Digory Kirke as a child is The Magician’s Nephew.

Published in 1955, The Magician’s Nephew is set earlier in Narnian history than the other Chronicles of Narnia novels. It follows Digory Kirke and Polly Plummer as they use magical rings to travel between worlds and witness the creation of Narnia.

The novel explains several famous elements of the series, including the origin of the wardrobe, the arrival of the White Witch, and the lamppost in Lantern Waste. As a child, Digory later becomes the professor whose country house appears in The Lion, the Witch and the Wardrobe.

Readers sometimes confuse publication order with the internal chronological order of the Narnia stories. The Magician’s Nephew was the sixth Narnia book published, but it is commonly treated as the first in the series’ fictional chronology.