“It seems, then,” said Tirian, smiling himself, “that the Stable seen from within and the Stable seen from without are two different places.”
“Yes,” said the Lord Dirogy. “Its inside is bigger than its outside.”
“Yes,” said Queen Lucy, “In our word too, a Stable once held something inside it that was bigger than our whole world.”
C. S. Lewis, The Last Battle, p. 140
For anyone familiar with the BBC series, Dr. Who, their time/space travel takes place in the Tardis, which is often referred to as being bigger on the inside than on the outside. The Last Battle was published in 1956. The first Dr. Who premiered in England on November 23, 1963, the day after C. S. Lewis died.