A prominent 17th-century nobleman, Greville was a renowned scholar, soldier, statesman and spy.

Like his dearest friend Sir Philip Sidney, he was also an accomplished author.

So talented, indeed, that some believe he was the true author of several of Shakespeare's works.

For years this has been little more than conjecture; fuel for the lively and often hostile debate between Anti-Stratfordians - those who deny that an ill- educated grain merchant and actor such as William Shakespeare could possibly have produced such a stunning oeuvre - and outraged traditionalists.

Now, however, the tantalising prospect of a definitive answer has been raised. More intriguingly still, the explanation, hidden in a series of clues scattered throughout his work and on the Warwick monument, is said to come from Fulke Greville himself.

In an echo of the themes in Dan Brown's blockbuster book and film, The Da Vinci Code, a historian has discovered what he claims to be powerful evidence that Greville had several manuscripts buried in his ornate memorial, including a copy of Antony And Cleopatra.