Mary Poppins delighted audiences for generations — the magical British nanny made Julie Andrews famous, Walt Disney rich and delivered royalties and prestige for author P.L. Travers.

But there was another character behind the scenes you've probably never heard of.

Illustrator Mary Shepard received little credit and little financial reward for her drawings of Mary Poppins, in the series of eight books by Travers.

The oversight is something a Queensland academic hopes to rectify.

University of Southern Queensland visual artist and researcher, Professor Margaret Baguley trawled through thousands of letters exchanged between Travers and Shepard and is supercalifragilisticexpialidocious-ly excited about what she found.

Dr Margaret Baguley trawled through thousands of original drawings and letters at a library in Princeton University. ( Supplied: Princeton University Library )

Dr Baguley attended a library at Princeton University in the United States where she discovered the original drawings for the Mary Poppins books, with handwritten notes from both the illustrator and the author — most of which have never been seen before outside of academic archives.

Dr Baguley was raised on Queensland's Darling Downs and has had a lifelong love of Mary Poppins.

"My interest was sparked because P.L. Travers lived near where I grew up in Warwick," she said.

"She lived in Allora for a short time where her father died, but not many people realised she was an Australian author."

In an effort to reveal Shepard's vital role in Mary Poppins, Dr Baguley examined the P.L. Travers archive at the Mitchell Library in Sydney and the E.H Shepard Archive at the University of Surrey in the UK, but it was the Cotsen Children's Library at Princeton that was her holy grail.

Photograph of Mary Shepard, c. 1925 (Ref no. EHS/F/14/2) From the E. H. Shepard Archive, University of Surrey. ( Supplied: University of Surrey )

The library held the original drawings for the Mary Poppins books and Dr Baguley received a Princeton research grant to access the library to study the communications between the author and illustrator.

"Something that the other two archives do not have were the original illustrations of the Mary Poppins books with comments from both P.L. Travers and Mary Shepard on the actual drawings with the decisions about how the various illustrations would look," she said.

"When I found out Princeton had the actual correspondence and the original drawings for Mary Poppins with annotations all over them, I thought, 'Oh my goodness, no-one has done this before'."

A collaboration that began almost by accident

Shepard's father was a well-known illustrator, famous for his drawings in Winnie the Pooh and The Wind in the Willows.

Travers first asked him to illustrate her children's books but he declined the commission claiming he was too busy.

"The story goes that she saw a Christmas card that Mary Shepard had illustrated and really liked the whimsical style and asked her to illustrate the Mary Poppins series of books," Dr Baguley said.

In the early 1930s, Shepard had recently graduated from London's Slade School of Fine Art.

"Travers was 10 years her senior and took on a mentoring role to assist in obtaining the types of drawings she wanted," Dr Baguley said.

"Shepard's illustrations provided readers with their first glimpse of Mary Poppins and were critical in helping the reader visualise the stories.

"She really set the aesthetic for how Mary Poppins looked."

An early drawing for the Mary Poppins books with notes from the author P.L Travers and illustrator Mary Shepard. Line illustrations by Mary Shepard © The Shepard Trust. Reproduced with permission from Curtis Brown Group Limited on behalf of The Shepard Trust ( Supplied: Princeton University Library )

The letters between the women reveal a warmth and an affection for one another but also reveal how the books evolved, Dr Baguley said

"It was such a revelation to see firsthand, through physical artefacts, the process undertaken by Travers and Shepard that resulted in the final images eventually published in the Mary Poppins' books," she said.

"Travers sent very detailed letters which included drafts of her stories and rough sketches and ideas for the types of illustrations she would like.

"Mary Shepard would read the stories and the suggestions from Travers and then undertake the complex process of visualising how the particular scene would look by sketching out initial ideas that were returned to Travers for feedback."

An early drawing of Mary Poppins by illustrator Mary Shepard with notes from her and author P.L Travers. Line illustrations by Mary Shepard © The Shepard Trust. Reproduced with permission from Curtis Brown Group Limited on behalf of The Shepard Trust ( Supplied: Princeton University Library )

There are handwritten responses on the sides of the sketches that also show how committed both women were to ensuring the illustrations remained accurate to the story.

"The Princeton University Library Research archives also revealed how much research Mary Shepard undertook for the books, including the number of buttons a policeman's uniform would have had in the Edwardian period," she said.

"The archives also contained a map of the locations in the Mary Poppins' books which featured the Banks' house in Cherry Tree Lane and surrounding areas, such as the park which helped her to ensure the perspective views in the illustrations were accurate."

Shepard left out of Disney deal

The partnership between the two women began amicably but ended badly in a protracted legal battle over the issue of copyright.

When Travers reached an agreement with Disney for the film rights in the 1960s after more than 20 years of negotiations, she did not include Shepard in the deal and it impacted their relationship.

"There are letters from Mary that are really quite sad, saying, 'Is there any part in this for my drawings?'" Dr Baguley said.

Shepard didn't get any of the millions Disney made at the box office, but she did manage to get a one-off payment, all thanks to Mary Poppins toes.

The original drawing of Mary Poppins and her parrot-handled umbrella by illustrator Mary Shepard. Line illustrations by Mary Shepard © The Shepard Trust. Reproduced with permission from Curtis Brown Group Limited on behalf of The Shepard Trust. ( Supplied: Princeton University Library )

Shepard drew Mary's feet in the first ballet position and when her lawyers realised that this was also used in the Disney movies, they had legal grounds for some compensation.

"Mary Shepard's solicitors said, 'Look at the feet, you know when Mary Poppins lands and her feet are turned out, that isn't written anywhere in the book, that's your own intellectual property and Disney have used that'," she said.

"I think she only received about a thousand pounds for that, something very minimal.

"I also found a whole folder of correspondence where she's [Shepard] having to sell the Mary Poppins drawings at Sotheby's because her house needed repairs …. that was just terrible."

Shepard died in September 2000, largely unrecognised for her role in bringing to life such an iconic literary character.

Dr Baguley hopes her research will finally celebrate Shepard's contribution to children's literature.

"People don't even know who the illustrator was and that she's left this wonderful legacy," she said.

"In time, both women became less well known than their creations, with Travers' fame subsuming Shepard's and Disney's subsuming them both.

"My work really is to highlight this pivotal role that she [Shepard] had because they're still using her pictures today."