During World War I she worked at a hospital and then a pharmacy, a job that influenced her work: many of the murders in her books are carried out with poison .

On 8 December 1926 , while living in Sunningdale in Berkshire , she disappeared for ten days, causing great interest in the press. Her car was found in a chalk pit in Newlands Corner , Surrey . She was eventually found staying at the Swan Hydro (now the Old Swan hotel) in Harrogate under the name of the woman with whom her husband had recently admitted to having an affair. She claimed to have suffered amnesia due to a nervous breakdown following the death of her mother and her husband's infidelity. Opinions are still divided as to whether this was a publicity stunt or not. Public sentiment at the time was negative, with many feeling that an alleged publicity stunt had cost the taxpayers a substantial amount of money. A 1979 film, Agatha , starring Vanessa Redgrave as Christie, recounted a fictionalised version of the disappearance. Other media accounts of this event exist; it was featured on a segment of Paul Harvey 's The Rest of the Story , for example.

In 1930 , Christie married a Roman Catholic (despite her divorce and her Anglican faith), the archaeologist Sir Max Mallowan . Mallowan was 14 years younger than Christie, and his travels with her contributed background to several of her novels set in the Middle East . Their marriage was happy in the early years, and endured despite Mallowan's many affairs in later life, notably with Barbara Parker , whom he married in 1977 , the year after Christie's death. Other novels (such as And Then There Were None ) were set in and around Torquay , Devon , where she was born. Christie's 1934 novel, Murder on the Orient Express was written in the Pera Palas hotel in Istanbul , Turkey , the southern terminus of the railroad. The hotel maintains Christie's room as a memorial to the author. The Greenway Estate in Devon, acquired by the couple as a summer residence in 1938, is now in the care of the National Trust . Christie often stayed at Abney Hall in Cheshire and penned two of her novels there: The Tale Of The Christmas Pudding and After The Funeral .

In 1971 she was made a Dame Commander of the Order of the British Empire .

Agatha Christie died on 12 January 1976 , at age 85, from natural causes, at Winterbrook House at Wallingford in Oxfordshire (formerly Berkshire). She is buried in the nearby St Mary's Churchyard in Cholsey .

Christie's only child, Rosalind Hicks, died on 28 October 2004 , also aged 85, from natural causes. Christie's grandson, Mathew Prichard , now owns the copyright to his grandmother's works.

Hercule Poirot & Miss Marple

Agatha Christie's first novel The Mysterious Affair at Styles was published in 1920 and introduced the long running character, detective Hercule Poirot who appeared in 30 of Christies novels and 50 short stories.

Her other well known character Miss Marple, was introduced in The Murder at the Vicarage in 1930, and based on Christie's grandmother.

During World War II, Christie wrote two novels intended as the last cases of these two great detectives, Hercule Poirot and Jane Marple — respectively, Curtain , in which Poirot is killed, and Sleeping Murder . Both books were sealed in a bank vault for over thirty years, and were released for publication by Christie only at the end of her life, when she realised that she could not write any more novels. These publications came on the heels of the success of the film version of Murder on the Orient Express in 1974 .

Like Conan Doyle , Christie was to become increasingly tired of her detective, Poirot. In fact, by the end of the 1930s, Christie confided to her diary that she was finding Poirot “insufferable”, and by the 1960s she felt that he was an “an ego-centric creep”. However, unlike Conan Doyle, Christie resisted the temptation to kill her detective off while he was still popular. She saw herself as an entertainer whose job was to produce what the public liked, and what the public liked was Poirot.

In contrast, Christie was fond of Miss Marple. However it is interesting to note that the Belgian detective's titles outnumber the Marple titles by more than two to one.

Poirot is the only fictional character to have been given an obituary in the New York Times , following the publication of Curtain in 1975.

Following the great success of Curtain , Christie gave permission for the release of Sleeping Murder sometime in 1976 , but died in January 1976 before the book could be released. This may explain some of the inconsistencies in the book with the rest of the Marple series - for example, Colonel Arthur Bantry , husband of Miss Marple's friend, Dolly , is still alive and well in Sleeping Murder (which, like Curtain , was written in the 1940s) despite the fact he is noted as having died in books that were written after but published before the posthumous release of Sleeping Murder in 1976 — such as, The Mirror Crack'd from Side to Side . It may be that Christie simply did not have time to revise the manuscript before she died. Miss Marple fared better than Piorot, since after solving the mystery in Sleeping Murder , she returns home to her regular life in Saint Mary Mead .

On an edition of Desert Island Discs in 2007, Brian Aldiss recounted how Agatha Christie told him that she wrote her books up to the last chapter, and then decided who the most unlikely suspect was. She would then go back and make the necessary changes to 'frame' that person.

You can view all Agatha Christie titles currently available for sale at the Curiosity Bookshop