All great crime writers have their favourite creations. Similarly, every great sleuth has his own preferred method of deduction.

Take the charming Parker Pyne, who relies upon an intuitive knowledge of human nature to solve the Problem at Pollensa Bay. Or Mr Satterthwaite, who seeks inspiration through his collaboration with the enigmatic Mr Quin in The Harlequin Tea Set mystery. Then, of course, there's Poirot, whose measured analysis of motive and opportunity is tested to the full in Yellow Iris, when he receives an anonymous call about a matter of life and death.

Agatha Christie was born in Torquay in 1890 and became, quite simply, the best-selling novelist in history. Her first novel, The Mysterious Affair at Styles, written towards the end of the First World War, introduced us to Hercule Poirot, who was to become the most popular detective in crime fiction since Sherlock Holmes. She is known throughout the world as the Queen of Crime. Her books have sold over a billion copies in the English language and another billion in over 100 foreign languages. She is the author of 80 crime novels and short story collections, 19 plays, and six novels under the name of Mary Westmacott.