1930. Their marriage lasted until Christie's death in 1976. She accompanied Mallowan on his archaeological expeditions, and her travels with him contributed background to several of her novels set in the Middle East. Other novels (such as Peril at End House) were set in and around Torquay, where she was raised. Christie drew on her experience of international train travel when writing her 1934 novel Murder on the Orient Express. The Pera Palace Hotel in Istanbul, the eastern terminus of the railway, claims the book was written there and maintains Christie's room as a memorial to the author. Christie and Mallowan lived in Chelsea, first in Cresswell Place and later in Sheffield Terrace. Both properties are now marked by blue plaques. In 1934, they bought Winterbrook House in Winterbrook, a hamlet near Wallingford. This was their main residence for the rest of their lives and the place where Christie did much of her writing. This house also bears a blue plaque. Christie led a quiet life despite being known in Wallingford; from 1951 to 1976 she served as president of the local amateur dramatic society. The couple acquired the Greenway Estate in Devon as a summer residence in 1938; it was given to the National Trust in 2000. Christie frequently stayed at Abney Hall, Cheshire, which was owned by her brother-in-law, James Watts, and based at least two stories there: a short story, "The Adventure of the Christmas Pudding", in the story collection of the same name and the novel After the Funeral. One Christie compendium notes that "Abney became Agatha's greatest inspiration for country house life, with all its servants and grandeur being woven into her plots. The descriptions of the fictional Chimneys, Stonygates, and other houses in her stories are mostly Abney Hall in various forms." During World War II, Christie worked in the pharmacy at University College Hospital (UCH), London, where she updated her knowledge of poisons. Her later novel The Pale Horse was based on a suggestion from Harold Davis, the chief pharmacist at UCH. In 1977, a thallium poisoning case was solved by British medical personnel who had read Christie's book and recognised the symptoms she described. The British intelligence agency MI5 investigated Christie after a character called Major Bletchley appeared in her 1941 thriller N or M?, which was about a hunt for a pair of deadly fifth columnists in wartime England. MI5 was
{
        'QUESTION: What was the duration of Agatha Christie\'s marriage?': 'ANSWER: Their marriage lasted until Christie\'s death in 1976.',
        'QUESTION: Where did Agatha Christie draw inspiration for her novel "Murder on the Orient Express"?': 'ANSWER: She drew on her experience of international train travel.',
        'QUESTION: Which hotel claimed to have been the location where Agatha Christie wrote "Murder on the Orient Express"?': 'ANSWER: The Pera Palace Hotel in Istanbul.',
        'QUESTION: What was one of the residences Agatha Christie shared with her husband?': 'ANSWER: They lived in Chelsea, first in Cresswell Place and later in Sheffield Terrace.',
        'QUESTION: What was the name of the property Agatha Christie and her husband purchased together in 1934?': 'ANSWER: They bought Winterbrook House in Winterbrook, a hamlet near Wallingford.',
        'QUESTION: How long did Agatha Christie serve as president of the local amateur dramatic society?': 'ANSWER: From 1951 to 1976.',
        'QUESTION: What role did Agatha Christie play during World War II?': 'ANSWER: She worked in the pharmacy at University College Hospital (UCH).',
        'QUESTION: What connection does Agatha Christie have with the thallium poisoning case in 1977?': 'ANSWER: A thallium poisoning case was solved using information from Christie\'s book, which helped identify the symptoms.',
        'QUESTION: Why was Agatha Christie investigated by MI5?': 'ANSWER: MI5 investigated Christie because a character called Major Bletchley appeared in her 1941 thriller N or M?.',
        'QUESTION: What is significant about the character Major Bletchley in Agatha Christie\'s work?': 'ANSWER: Major Bletchley appears in a thriller about a hunt for a pair of deadly fifth columnists in wartime England.'
    }