Agatha Christie, the Queen of Crime, was pronounced by UNESCO in 1961 as the world's best selling author. Today she is recognised as the bestselling novelist of all time. Astonishingly, in 1948, 25 years after the publication of her debut novel, The Mysterious Affair at Styles, Penquin released a million of her novels - 10,000 copies of ten of her titles - on the same day.

Despite all of this, Christie saw herself as an ordinary housewife, creating a public image intended to conceal her real self.

There have been many biographies of Christie, which have attempted to reconcile the two personas, searching for clues to the puzzle that Christie appears to have been.

Now, historian and TV presenter Lucy Worsley enters the fray with a new biography subtitled A Very Elusive Woman, stating "in this book I'd like to explore why Agatha Christie spent her life pretending to be ordinary" when the truth was that she was "thrillingly, scintillatingly modern".

Christie went surfing in Hawaii, loved fast cars and was intrigued by the new science of psychology, which helped her through mental illness and informed her novels.

Although there's not much new in Worsley's biography, she does contribute something she considers "radical" [sic] in her investigation into Christie's motives in disappearing for 11 days in 1926.

Worsley writes, "It's frequently said that Agatha remained silent about this notorious incident for the rest of her life. But that's incorrect. I've pieced together the surprising number of statements she did in fact make about it. And looking at them carefully, I believe much of the so-called mystery fades away".

Worsley argues that it was not a publicity stunt, nor an attempt to frame her husband for her murder but rather a "distressing episode of mental illness brought on by the trauma of the death of her mother" and the discovery of her husband's mistress and his demands for a divorce.

Agatha herself wrote that when she left that night she was "in a state of high nervous strain with the intention of doing something desperate". Worsley believes that, in Harrogate, she reinvented herself as the stylish, well-dressed Mrs Teresa Neele, living an imaginary life to escape the unbearable life of Mrs Christie.

The end result was a well-documented fear of "opening up", especially to the press. Christie had become the elusive woman.

This is an affectionate, very readable biography. Worsley is a clever communicator and I wonder how long it will be before she presents a TV program on the "elusive" Agatha Christie.