Rosalind Hicks, who died on October 28 aged 85, fought to protect the reputation and literary legacy of her mother, the crime novelist Dame Agatha Christie, after her death in 1976.
An unashamed fan of her mother's books from childhood, when the author would read her novels to her family over dinner, Rosalind Hicks said she could "read them over and over again and still find a lot to enjoy in them".
Before her death, Agatha Christie had established a limited company to own the rights to her books and sold a majority share to a subsidiary of the food giant Booker. The family, however, retained a minority holding which gave them a right of veto over any new treatment or publication of her works.
Agatha Christie herself had firm ideas about how her books should be dramatised and did not like most of the film versions of her work, the one exception being Sidney Lumet's Murder on the Orient Express, which she enjoyed.
Rosalind Hicks was determined to remain true to her mother's vision and to protect the integrity of her creations, considering what her mother's wishes would have been with regard to the exploitation of the enormous numbers of copyrights in every market in the world.
She kept a firm distance from "merchandise" and, like her mother, disapproved of most film dramatisations, though she felt that David Suchet as Poirot and Joan Hickson as Miss Marple had come closer to the looks and spirit of their characters than any other actors.
She was acutely sensitive to criticism that her mother's books were "all the same, with a Twenties or Thirties atmosphere and stock characters", pointing out that she wrote more than 70 novels between 1920 and 1973 and all were set at the time of writing. She saw no reason to update them and resisted attempts to try.
In 1995, when the film company Polygram proposed to give a 1990s spin to its version of Towards Zero, by introducing incest into the story, Rosalind Hicks forbade the use of the title, the author's name or the original names of the characters. The company renamed the picture Halcyon Days. She was also said to be upset by an ITV adaptation of Sparkling Cyanide, in which Agatha Christie's victim, a middle-aged industrialist, turned into a premiership football club chairman. She found herself having to field applications to write an official biography of her mother's life. Eventually, she picked the writer Janet Morgan, whose study was published to acclaim in 1984, but there were also several unofficial biographies.
Like her mother, Rosalind Hicks was particularly sensitive to speculative accounts of the "missing 11 days" in December 1926, when Agatha Christie disappeared from her home, sparking a police hunt and a media circus that ended when she turned up in a Harrogate hotel, having apparently lost her memory. Agatha Christie had always refused to answer questions about the period, and the Christie family had maintained silence for years.
In 1978 Rosalind Hicks unsuccessfully sought an injunction against the producers of Agatha (1979), a fictional speculation on what might have happened starring Vanessa Redgrave, to prevent its being distributed.
She was also upset by Agatha Christie and the Eleven Missing Days (1998), in which the writer Jared Cade claimed, based on interviews with members of another side of the author's family, that her disappearance had been planned by the writer herself as an elaborate method of humiliating her unfaithful husband. But the episode backfired spectacularly when her private revenge became public property and her wretched husband was suspected of murdering her. The amnesia story, Cade suggested, had been cooked up by relations of Agatha Christie with whom she had taken refuge, in order to prevent further intrusion.
Rosalind Hicks was said to be furious with Cade's account, and, at the annual meeting of the Agatha Christie Society in 1998, her son, Mathew Prichard, launched a virulent attack on Cade's theory, advising members of the society not to buy the book.
Rosalind Hicks continued to insist that Agatha Christie's disappearance had been occasioned by a nervous breakdown brought on by her mother's death and the failure of her marriage. She recalled going with her governess to her aunt's home in Cheshire, Abney Hall, where her mother went to stay after she was found, and finding that "she did not remember anything we had been doing together or even the stories she used to tell me".
Rosalind Margaret Clarissa Christie was born on August 5 1919 at Ashfield, her mother's family home at Torquay. Agatha Miller had married Rosalind's father, Colonel Archibald Christie, an aviator in the Flying Corps, in 1914.
Shortly after Rosalind's birth, the family moved to London. In 1920 Agatha Christie's first book, The Mysterious Affair at Styles, was published by Bodley Head. Her second was published in 1922, and from then on they appeared roughly at yearly intervals.
Rosalind was bright, affectionate, pretty, direct and tremendously energetic. "She was the kind of child who was never still for a moment," her mother recalled; "who, if you returned from a long and gruelling picnic, would say brightly: `There's at least half an hour before supper - what can we do?' It was not unusual to come round the corner of the house and find her standing on her head."
Her father adored her. Agatha, too, loved her (Rosalind recalled her mother as "loving and understanding - always gentle and kind"), but maintained a certain distance.
After her parents' divorce in 1928, Rosalind managed to remain staunchly loyal to both. She continued to live with her mother and her mother's second husband, the archaeologist Max Mallowan, of whom she was very fond; but she continued to see her father often and they remained on good terms.
Rosalind grew into a tall, good-looking and forthright young woman and, after education at Benenden followed by a period in Switzerland and France, she returned home to "do the Season" and was adjudged a success.
In 1938 Agatha Christie, her husband and Rosalind moved to Greenway, a 278-acre estate on the banks of the river Dart, the setting for several of her books.
In 1940 Rosalind married Hubert Prichard and had a son, Mathew, in 1943. Her husband was killed a year later on active service, and in 1949 she married her second husband, Anthony Hicks. Ten years later Agatha Christie transferred the Greenway estate into her daughter's name, and the Hickses moved to the main house in 1967. The couple worked hard to develop the gardens until 2000, when they transferred the land to the National Trust.
In 1993 Rosalind Hicks became president of the newly-formed Agatha Christie Society, with Joan Hickson and David Suchet as vice-presidents.
Rosalind Hicks is survived by her husband and their son.
Copyright The Daily Telegraph (2004)