[The Squatter of Amon Rûdh]

According to Humphrey Carpenter's biography, Tolkien once told Nevill Coghill that he had modelled Treebeard's mannerisms of speech on "the booming voice of C.S. Lewis". Although the words are Carpenter's and not those of Tolkien or Coghill, I see no reason to doubt the truth of them.

As for there being any real interpolations, I think that Tolkien was too subtle to insert any person, place or concept into his writing as it was in the real world. He might have taken Lewis' voice for Treebeard, but the rest of the character is probably quite unlike him. Often he drew comparisons between his fiction and the real world, but only in the way that someone might compare something with a person, place or event from natural mythology. For example, after a trip to Italy in 1955, he wrote: "Venice seemed incredibly, elvishly lovely - to me like a dream of old Gondor, or Pelargir of the Númenorean Ships before the return of the Shadow." In his letters, he compares the Númenoreans with the ancient Egyptians in their burial practices, and he said that Siamese cats belonged "to the fauna of Mordor". This does not, of course, presume that Númenor is ancient Egypt or that there really were cats in Mordor: Tolkien simply saw parallels, as he expected his readers to do. Too close a portrayal of any place, person, situation or event would have smacked too much of allegory, from which he was quick to dissociate his fiction.