C.S. Lewis, the author of the Narnia stories, was a man of secrets. But there can be no doubting what his greatest and most closely guarded secret has been — that’s if the Oxford college chaplain Dr Michael Ward is to be believed.

Dr Ward is the writer who claims to have cracked one of the most fascinating literary mysteries by uncovering the secret that Lewis not only took to the grave, but managed to keep from readers and scholars for more 60 years.

For while countless millions of us have simply enjoyed The Lion, the Witch and the Wardrobe and the other Narnia books as wonderful stories, with most recognising the obvious Biblical allegories, Dr Ward believes something else is going on in the books — a secret Narnia code no less, that critics, biographers and even C.S.Lewis’s Oxford friends, like J.R.R Tolkien, all simply missed.

This cryptic code, he argues, gives the Narnia chronicles another layer of meaning — a ‘deeper magic’ you might say — that reveal Lewis to be an even greater writer than his most ardent admirers imagined.

No doubt about it, in the literary world, the new chaplain of St Peter’s College has certainly been causing quite a stir.

His book, Planet Narnia, which has already sold 10,000 copies, last week was published in paperback by Oxford University Press, with a new edition planned for the end of the year that happily coincides with the cinema release of the Voyage of the Dawn Treader.

The BAFTA and Emmy Award-winning director Norman Stone, who made the original Shadowlands film about Lewis’s marriage, was so impressed with Dr Ward’s ‘discovery’ that he made it the subject of a documentary for the BBC, which is soon to be released on DVD.

And, even more encouraging for the chaplain, has been the impressive line-up of leading authorities on Lewis expressing enthusiasm for his book, most notably Walter Hooper, who was a personal friend of the author and literary adviser to the estate of C.S. Lewis.

Mr Hooper, who lives in North Oxford, commented: “I cannot contain my admiration. No other book on Lewis has ever shown such comprehensive knowledge of his works and such depth of insight. This will make Michael Ward’s name.”

So, what is the groundbreaking discovery that is said to unlock the secret theme behind some of the world’s best known books, while shedding new light on the workings of a great author’s mind?

Essentially, Dr Ward says that the planets are at the heart of the Narnia books, reflecting Lewis’s lifelong engagement with Medieval astronomy. The Narnia books are, in fact, the literary equivalent of Holst’s The Planets.

Or, to be more precise, Dr Ward says he has established that the former Oxford University don, who died in 1963, deliberately constructed the Chronicles of Narnia out of the “imagery of the seven heavens”.

“C.S. Lewis had a huge interest in the planets and in the gods associated with them, an interest that stemmed from his childhood,” said Dr Ward, who for three years lived in The Kilns, the home Lewis shared for many years with his brother in Risinghurst, which now owned by the C.S. Lewis Foundation.

“The planets appear with tremendous frequency in his poetry, most notably in The Planets, a long, alliterative poem he wrote in 1935. He was fascinated by them as an imaginative writer, a literary historian and as an amateur astronomer.”

And they are there woven deep into the Narnia books as well, with the stories packed with planetary imagery. It is simply a matter of being able to spot the clues, with planet images determining the overall shape and feel of each story.

According to astronomers before Copernicus, the seven heavens contained the seven planets that revolved around Earth and exerted influences over people and events.

Dr Ward’s book claims that each of the seven books were written to express the qualities and personality of one of the seven planets, beginning with Jupiter, his personal favourite, in The Lion, the Witch and the Wardrobe.

So why would Lewis have gone to such trouble to write the chronicles to a secret theme, with the risk of his cleverness never being recognised?

Well, for a start, we have to remember that Lewis was a complex figure, who delighted in secrets, maintains Dr Ward. “George Sayer, who was a pupil and then a friend of Lewis for 30 years said he ‘never ceased to be secret’. The clearest example of Lewis’s ability to be secretive is the fact that he kept his marriage to Joy Gresham secret for the best part of a year, even from close confidants such as Tolkien.”

When Lewis published his autobiography, Surprised by Joy, one cynical friend said that so many things had been kept out it should have been entitled Suppressed by Jack (Jack being Lewis’s nickname).

Further evidence is presented that the great man could be less than Washingtonian in his candour, such as when he deliberately misled a fox hunt, shouting to the riders: “Hallo, yoicks, gone that way,” pointing in the direction opposite to the one the fox had taken.

There would also have been literary reasons why he might have wanted to keep his imaginative blueprint for the Narnia books a secret. Lewis viewed atmosphere as one of the main qualities of a good story, once declaring himself interested in imaginative “hiddenness”.

Later, when Dr Ward discussed his idea with the Rt Rev Simon Barrington Ward, the former Bishop of Coventry, who had known Lewis well, he was assured that it was “the sort of thing that Lewis would do”.

Dr Ward studied theology at Regent’s Park College, Oxford, and theology at Cambridge, where he went on to become chaplain of Peterhouse from 2004 to 2007.

He chuckles that, until the Planet Narnia book, his chief claim to fame was that he handed a pair of X-ray spectacles to James Bond when appearing in the film The World is Not Enough as an extra. Ironically, he has also edited a book on Heresies and How to Avoid Them, as well as the Cambridge Companion to C.S. Lewis.

For his Narnia ‘eureka’ moment only came after some 30 years of reading Lewis and ten years teaching undergraduates. “I also spent three years sleeping in the room where he slept and working in his study at The Kilns,” he adds.

However, he was in Cambridge working on his doctoral thesis on Lewis and language when ‘the breakthrough’ happened. Before going to bed one night he took a copy of Lewis’s collected poems and began reading The Planets.

Seeing the phrase ‘winter passed/ And guilt forgiven’ the thought occurred that this formed the centrepiece of the first Narnia tale.

In his mind he began to view Aslan as a figure stirring awareness of Jupiter — kingly, magnanimous and festive.

Other planet-to-book relationships began to fill his mind as he came to believe that each one of the seven planets had been translated into Narnia plots.

“I did not shout ‘eureka’ and run naked down the street like Archimedes, but I did jump from my bed in a state of undress and began to pull books from my shelves, chasing links from work to work,” he now recalls.

So why did everybody else miss it? Well, in part, it may be down to Tolkien, to whom C.S. Lewis read chapters, he says. “Tolkien was the first to voice the view that the chronicles are a hodge-podge and his opinion has rumbled on in critical assessments of the series ever since,” argues Dr Ward.

The author of The Lord of the Rings, who was meticulous in his own writing, found the wide range of literary traditions which Lewis drew on to be confusing. Tolkien’s view that it was a mish-mash set the critical agenda, Dr Ward argues, and the hidden meaning woven into the seven fairytales was overlooked.

The other key factor was that a second level to the books clearly already existed, with the obvious Biblical allegories and Aslan created as a Christ-like figure. Most Lewis scholars have been Christians, and astrology, in any case, has been a subject disdained by academics.

Whatever the real meaning of the chronicles, Planet Narnia, first published in 2008, has certainly changed the life of the chaplain.

He has embarked on lecture tours in America and the UK. People write to him to say that Lewis’s planetary secret has inspired them to write and compose music.

“There is something about this idea of Narnia and the heavens that captures the imagination,” said Dr Ward, waving the cover of his next book The Narnia Code.

And as the 60th anniversary of the publication of The Lion, the Witch and the Wardrobe approaches, it is pleasing to imagine it all being a don’s playful literary experiment.

“Well, Lewis did have a playful side to his character,” said Dr Ward. “Lewis may have wondered, ‘how long will it take them?’.”

Whether he is right or not, Dr Ward’s efforts would surely have brought a smile to the great man’s face.