The Golden Age of Murder. Martin Edwards

Hotel in Istanbul has an Agatha Christie room, and her face smiles from a billboard welcoming tourists to Gran Canaria. On the 120th anniversary of her birth, cooks around the world baked a Delicious Death cake from a recipe by Jane Asher. The book with the thickest spine in the world has been created from the complete Miss Marple stories. In Harrogate, a plaque in the Old Swan Hotel (formerly the Hydropathic Hydro) commemorates her disappearance, the reason for which continues to provoke debate. Agatha Christie is, in short, an icon whose name is synonymous with detective fiction and mystery.

      The enduring nature and astonishing scale of her fame would have amazed, and possibly appalled her. Not only was she genuinely modest, she was fanatical about preserving her privacy. She had always been shy, but the media frenzy that surrounded her disappearance left her with a lifelong detestation of the Press.

      At first sight, Christie seems as genteel as her books are supposed to be. With Christie, however, nothing was quite as it seemed. In person, she combined a straightforward outlook on life with hidden depths, just as her simple and accessible writing style contrasted with her devious plots. Her father was American, and from childhood she spent long periods abroad, gaining a breadth of understanding and experience of the world that helps to explain why her work has enjoyed unceasing popularity when so much more sophisticated fiction has vanished from sight.

      Agatha Mary Clarissa Miller was born on 15 September 1890, the third child of Frederick and Clara Miller. Frederick had inherited enough money from the family business not to need to work, and not long after Agatha’s elder sister Margaret (known as Madge) was born, the family settled in Torquay. Frederick was good-natured but lazy, and his failure to keep a close eye on the family fortune proved financially calamitous. To economize, he let the Torquay house, and took his family to France for over six months. Agatha enjoyed such an idyllic summer in Pau that she never went back there, unwilling to diminish the magical memories of that first foreign adventure. Her novels are stereotypically associated with settings in country houses and seemingly Home Counties villages for which detective novelist Colin Watson coined the generic term ‘Mayhem Parva’. In fact, a high proportion of her stories are set overseas. This reflects her love of travel, but above all her core belief that, in its fundamentals, human nature is much the same everywhere.

      Madge was regarded as ‘the clever one’ in the family, and attended boarding school, but one of Clara’s unorthodox ideas was to school Agatha at home. Frederick Miller’s health deteriorated along with the family finances, and he died in 1901. Money was short, but Madge had married James Watt, who came from a wealthy Mancunian family, and Agatha often stayed with them at Abney Hall in Cheshire. She loved Abney, and fictitious versions of it appeared in After the Funeral and ‘The Adventure of the Christmas Pudding’. After a brief and unsatisfactory spell at a Torquay school, attending two days a week, she completed her education at three pensions in France.

      She lived in her imagination, and loved writing stories and poems. Her instinct was to watch and listen to others rather than take centre stage herself. A keen eavesdropper, she gathered plot ideas from stray phrases in overheard conversations between strangers. She was as curious about other people as she was reluctant to reveal her own thoughts. Her innate modesty meant she felt under no compulsion to talk too much, and so she never gave herself away.

      She wrote a novel set in Cairo, where she and her mother had taken a three-month holiday, but a literary agent, Hughes Massie, turned Snow upon the Desert down. Undaunted, she continued to write, as well as taking singing lessons, while receiving plenty of overtures from young men attracted by her serene manner and quiet good looks. Tall, slim and pale-haired, she rejected several marriage proposals before becoming engaged to Reggie Lucy, a major in the Gunners. Yet she broke with Reggie after meeting a dashing young airman.

      Lieutenant Archie Christie was the son of a judge in the Indian Civil Service, and Christie later said she fell for him because she found him unpredictable and fascinating. When war broke out, she realized he was likely to be killed. Three days before Christmas, he suddenly obtained leave from duty and they decided to marry. The wedding took place on Christmas Eve 1914, and Archie returned to France on Boxing Day. Life at this time was heady, exhilarating, and impulsive. It was also frighteningly insecure. Agatha’s brother Monty, a feckless charmer, was badly wounded while serving with the King’s African Rifles, and although he survived, he suffered psychological damage. To Clara’s distress, he liked to take up his revolver and shoot at people passing the family home in Torquay – a hobby Christie gave to a character, decades later, in her play The Unexpected Guest.

      Archie was decorated for bravery and promoted to the rank of colonel before being invalided out of the Royal Flying Corps. At one point the couple did not see each other for almost two years. Agatha became a V.A.D. (Volunteer Aid Detachment) nurse, later transferring to the dispensary. A rather sinister pharmacist who told her he enjoyed the power afforded by dealing with poisons stuck in her mind, and nearly fifty years later, provided her with a key character in The Pale Horse. She blew up a Cona coffee maker whilst attempting the Marsh test to detect the presence of arsenic, but acquired an extensive knowledge of poisons, which she soon put to use – in fiction.

      Madge shared Agatha’s enthusiasm for detectives such as Sherlock Holmes and his French rivals Arsène Lupin and Joseph Rouletabille, and challenged her to write a whodunit. Having encountered a few Belgian war refugees, Christie decided that her detective would be Belgian too. She created someone who was vain but brilliant: Hercule Poirot. His foreign nationality was a clever stroke, and so was his conceit: British people were often suspicious of foreigners, and distrustful of cleverness. Christie poked fun at her fellow countrymen’s insularity, while making it plausible that suspects who concocted ingenious murder schemes made the catastrophic mistake of underestimating this seemingly ridiculous figure, with his broken English, extravagant moustache and insistence on using ‘the little grey cells’ of the brain. Christie’s prime literary influence was Conan Doyle, and she equipped Poirot with an amiable if rather obtuse Watson in Captain Arthur Hastings.

      Christie finished The Mysterious Affair at Styles in 1918, and the following year she gave birth to Rosalind. After a series of rejections from publishers, John Lane offered a less-than-generous contract which gave him an option over her next five books. She made the revisions he asked for, and her ingenious country house mystery finally appeared in the US in 1920 and in Britain the following year. Next came The Secret Adversary, a light and breezy thriller which introduced a young couple who went on to marry and to feature in four subsequent books, the last published more than half a century after the first. Tommy and Tuppence Beresford represent wish fulfilment on Christie’s part. She imagined herself as the lovely, sharp-witted Tuppence, while the courageous and eternally reliable Tommy was an idealized portrait of the man she thought she had married.

      In January 1922, Christie and Archie took the extraordinary step of leaving their young daughter for almost a year so that they could take part in a ‘Mission to the Dominions’. This was an international publicity exercise meant to pave the way for the forthcoming British Empire Exhibition. The grand tour was the brainchild of Major Belcher, a friend of Archie’s with a genius for self-promotion, the highlight of whose war service was a spell as Controller of the Supplies of Potatoes. Belcher offered Archie, who had worked in the City since the war, the job of financial adviser to the mission, and Agatha’s travel expenses were covered, with a month’s holiday in Honolulu thrown in. Archie’s employers were unwilling to keep his job open for him, but he was bored with civilian life, and Agatha loved to travel. She said in her autobiography: ‘We had never been people who played safe.’

      Although Madge and her mother agreed to look after Rosalind, Madge felt Agatha should have stayed in England, but Clara Miller was supportive, arguing that a wife’s priority was to be with her husband. Agatha fell in love with South Africa, and the experience provided material not only for her next book, but also for creating the make-believe life of Mrs Teresa Neele. On board ship, she often played bridge, and sometimes quoits, once defeating the captain. In Waikiki, the couple were among the first British people to master the art of stand-up surfing. An added pleasure for Agatha was the chance to show off her figure in an emerald green wool bathing dress.

      The tour was long and often gruelling, but although Belcher proved a cantankerous and selfish