The multi-award-winning Disney musical Mary Poppins will be 50 years old in 2014 and to mark the occasion a Hollywood film of its author’s life is being made, starring Tom Hanks and Emma Thompson.

But while the 1964 film starring Julie Andrews remains one of the most popular Hollywood pictures ever made, few people know that the author, Pamela Lyndon Travers, began writing her series of books about a “tart and sharp, rude, plain and vain” nanny with a magical touch while she was living at the 16th century Pound Cottage in Mayfield in 1933.

It was to this thatched cottage that Pamela had come to recover from pleurisy and during her convalescence had revived the story idea that had originated during her childhood in Australia.

However, in contrast to the virginal character of Mary Poppins, Pamela had brought her own somewhat unconventional love life to Sussex in the form of Madge Burnand, the daughter of playwright Sir Francis Burnand, who Pamela lived with for more than a decade. Moving out of the London flat they rented in 1932, they set up home together in Sussex.

“Her relationship with Madge is ambiguous,” wrote Valerie Lawson in her biography of Pamela entitled Mary Poppins, She Wrote. It was “intense”, and a bare-breasted photo of Pamela “is likely to have been shot by Madge, but that is hardly evidence that the two women were sexually intimate”.

It’s no wonder, as Lawson wrote, that Pamela “deeply resented anyone prying into her personal life” and it was only very late in her somewhat bizarre and complex life that a biography could be written at all.

“If you are looking for autobiographical facts,” Pamela herself wrote, “Mary Poppins is the story of my life.”

The parallels are striking. Just like Mr Banks, the distracted banker who employs Mary Poppins as nanny for his children at 17 Cherry Tree Lane, Pamela’s father Travers Goff was a banker, albeit a drunken one who was demoted to clerk. Of Irish descent, he died when Pamela, whose real name was Helen Lyndon Goff, was seven. After their mother tried to drown herself three years later young Pamela began creating stories about flying horses to cheer up her younger sisters. Later, Pamela told the New York Times that “sorrow lies like a heartbeat behind everything I have written”.

The family moved from their original home in Maryborough, Queensland, Australia, to Bowral in New South Wales, where a relative owned a sugar plantation. Pamela received a private education and as a teenager wrote poetry that appeared in Australian periodicals. But at 17 she decided to be an actress and headed for Sydney, where she joined a repertory company and performed Shakespeare, supplementing her income as a journalist.

By 1923 her poems had taken a rather erotic turn and she became besotted with Irish mythology. She studied with the spiritual teacher George Gurdjieff, in a period that certainly influenced the stories of her mystical nanny that she began to write at Pound Cottage.

The first book was an instant hit, attributed to its unusual mix of the everyday with the fantastical, and subsequent books followed.

When the Hollywood movie maker Walt Disney came across the Mary Poppins books, he knew they had a kind of magic, but Pamela resisted his offers to the rights for 14 years, and even then insisted on many conditions, including no animation.

She cried when she saw the film version at the 1964 world premiere. The film featured Julie Andrews playing Mary Poppins as sweet not tart, pretty not plain, and firm not rude, and with lengthy animated sequences.

Pamela hated the film, even though it made her wealthy for the rest of her life, and as she grew older she became more brittle. “She felt very much alone,” Lawson wrote. “She did not make friends very easily, but I don’t want to make out that she was always miserable.

When she was in middle age, she was quite a charming and lively person... [but] she became a rather self-important, morose kind of Pamela.”

Perhaps the strangest episode of the author’s life came at the age of 39, in 1939, after Madge had moved out and Pamela had published her second successful Mary Poppins book. Still living in England but now working for the Ministry Of Information, it is thought Pamela embarked on another long-term relationship with American Jessie Orage, and an affair with an older married man.

She then tried, unsuccessfully, to adopt her 17-year-old maid, before travelling to Ireland to adopt a baby. Shown twin baby boys, she chose the one she liked best after refusing to take both and named him Camillus. On getting him home she was horrified by his persistent crying and considered putting him in a babies’ home. Ultimately she sent him to boarding school as soon as possible.

For the rest of her life, Pamela lived and worked in London, and died at the age of 96 in 1996. Camillus died last November, his life blighted by alcohol but funded by the riches of the Mary Poppins film.