SAVING MR BANKS (PG, 125 mins) **** Starring Emma Thompson, Tom Hanks, Paul Giamatti, Bradley Whitford, Jason Schwartzman, BJ Novak, Colin Farrell, Ruth Wilson, Annie Buckley, Rachel Griffiths, Kathy Baker. Director: John Lee Hancock.

Almost 50 years after Mary Poppins first charmed cinema audiences, Robert Stevenson’s magical film continues to cast a spell with its lively characters, heart-warming sentiment and hummable tunes.

Yet the colour-saturated fantasy, which won five Oscars including Best Actress for Julie Andrews, almost never materialised on the big screen.

Australian-born British novelist PL Travers, who penned the series of books on which the film was based, famously rebuffed Walt Disney’s efforts to purchase the rights for more than 20 years.

When she finally relented in 1961, Travers was granted script approval, and archive recordings of the meetings between the author, screenwriter Don DaGradi and songwriter brothers Richard and Robert Sherman reveal her resistance to the Disney-fication of her beloved nanny.

That infamous tug-of-war between the writer and Hollywood filmmaker is recreated in Saving Mr Banks, an elegant and witty comedy emboldened by tour-de-force performances from Emma Thompson and Tom Hanks.

When we first meet Travers (Thompson), she has fallen on hard times yet refuses to entertain the advances of Disney (Hanks).

“I know what he’s going to do to her. She’ll be cavorting... and twinkling!” seethes the writer.

Yet the filmmaker is persistent, telling Travers that, “20 years ago I made a promise to my daughters that I would make your Mary Poppins fly off the pages of your books.”

Eventually, Travers flies to America to meet Disney and his team including Don DaGradi (Whitford), Richard Sherman (Schwartzman) and his brother Robert (Novak), whose twee songs fail to curry favour.

“These books do not lend themselves to prancing and chirping,” Travers rebukes.

Despite a touching friendship with her chauffeur Ralph (Giamatti), Travers is unmoved by the re-imagining of her cherished text and eventually she snaps, telling Disney: “Mary Poppins is not for sale. I won’t have her turned into one of your silly cartoons.”

Something has to give and it is Disney who realises that if he is to win over the author, he must confront the ghosts of his own past.

Saving Mr Banks is an embarrassment of riches from the stunning lead performances to John Lee Hancock’s assured direction and Kelly Marcel and Sue Smith’s script, which intercut events in 1960s California with vignettes from Travers’s turbulent childhood in 1906 Australia.

Thompson is formidable, tossing verbal grenades at anyone who dares to besmirch Travers’s literary creation, while slowly revealing the chinks in the writer’s armour.

Screen chemistry with Hanks is delightful.

“I could just eat you up,” coos Disney at one point. “That would be inappropriate,” retorts Travers tartly.

Hancock strikes just the right balance between humour and heart-tugging sentiment, culminating in a glitzy world premiere screening where Travers finally shares Mary with the rest of the world and in so doing, sets herself free.