AN AMERICAN professor believes he has uncovered a book that was being jointly written by literary giants CS Lewis and JRR Tolkien.

Lewis, author of The Chronicles of Narnia, was a close friend of Tolkien, who wrote The Lord of the Rings, and the two Oxford dons discussed their books together as members of The Inklings, who famously met at The Eagle and Child pub in St Giles.

However, it was not thought the two writers, who individually sold millions of books, ever collaborated on a literary project — until now.

Prof Steven Beebe, of Texas State University, described his “Indiana Jones moment” when he was looking through the large CS Lewis archive at the Bodleian Library for new insights into the author.

It is known that in the 1940s Lewis and Tolkien spoke about writing a book together. But it was not until Prof Beebe opened up a notebook, on which Lewis had written the word “scraps”, that evidence came to light suggesting the book was started.

Sadly, for enthusiasts of The Hobbit and The Lion, The Witch and the Wardrobe, the book they wanted to produce was about language rather than being the ultimate fantasy novel.

Prof Beebe, who is in Oxford this month teaching a course on CS Lewis at St Hilda’s College, said Tolkien had, in a letter to his son Christopher, referred to a collaborative book to be called Language and Human Nature.

It was to be published in 1950, but never saw the light of day and scholars have always thought it was never even started.

But Prof Beebe said he is convinced Lewis had written the opening pages of the book in a notebook kept in the Bodleian.

Prof Beebe discovered it by turning the little notebook upside down and reading from back to front.

The notebook also contains early fragments of two Narnia stories — The Magicians’s Nephew and The Voyage of the Dawn Treader.

Written in Lewis’s distinctive handwriting, the opening sentence said: “In a book like this, it might be expected that we should begin with the origins of language.”

But then the American academic noticed Lewis wrote about “our statements” and used the phrase the “authors consider”.

Prof Beebe said: “I told my wife it was my Indiana Jones moment, with me as the mild-mannered professor making a discovery of a lifetime.”

Prof Beebe consulted Walter Hooper, Lewis’s biographer and former secretary, who lives in North Oxford, to confirm it was the great man’s handwriting.