As a kid, we had Mary Poppins taped off the television, and so the ad breaks became part of the film. One ad in particular really spooked me: Yul Brynner’s posthumous anti-smoking message. The skin drawn tight over Brynner’s skull was intended to shock, and it did: he seemed to be death and disease personified, and I couldn’t bear to look at him. It occurred only once on the tape – in the ad break after “Feed the Birds” – and so that song became invested with dread, knowing as I did what came next. Its placement was not altogether inappropriate: the film’s tone steadily darkens from that point. As much as I love the movie’s songs and its colourful adventures, to me it has a pall of melancholy, much like the smog the children survey from the rooftops late in the film. It’s the melancholy of transience: the movie’s enchantments never last. The chalk drawings wash away in the rain. Mary Poppins flies away alone, forgotten by her charges. In a way, the Yul Brynner ad, with its solemn opening – the actor’s dates of birth and death on a black background – was the perfect accompaniment.

That melancholy is mostly absent from P.L. Travers’ book. Written in 1934 (and updated throughout Travers’ lifetime – my 1981 edition contains references to Queen Elizabeth), the world it describes seems more Edwardian than Great Depression (let alone that of the current queen). It’s an idyll, with its streets lined with cherry trees and its affectionate nod towards Empire (the Admiral with his house “built exactly like a ship”). The Banks family is not the dysfunctional unit of the film but a happy, shabby family who live in a house that’s “dilapidated and needs a coat of paint.” (Mr. Banks “said to Mrs. Banks that she could have either a nice, clean, comfortable house or four children. But not both, for he couldn’t afford it.”) They live in a comfortable state of chaos. Mary Poppins’ arrival does not answer any particular emotional need in the children; their adventures under her care are pure larks. The Mary of the book is a rather tart creation, vain and cross; she resolutely refuses to explain herself. In this, she’s much like the author: the book is a series of hasty sketches, often left dangling, and there’s a certain asperity in Travers’ refusal to round things out or to link them together.

In Saving Mr. Banks, the recent movie about the making of the 1964 Disney adaptation, the portrait of Travers goes beyond asperity. As played by Emma Thompson, Travers is a joyless martinet, her lips breaking their straight line only to curl in disgust, her arms folded tightly across her breasts. It’s taken for granted in Saving Mr. Banks that Disney’s movie is an eternal classic, and so Travers’ objections to his methods are presented as fussy and foolish – on the wrong side of history. Worse, her issues with Disney’s adaptation are not even grounded in differences in sensibility, but in that old movie chestnut – the childhood trauma that explains everything. (Half the movie is spent in flashbacks to Travers’ childhood in Queensland.) The movie implies that you’d have to be emotionally disturbed to object to cartoon penguins.

A tape of Travers working with the movie’s songwriters plays over the closing credits, and it makes a nonsense of everything that’s gone before. Travers notices details – she complains that the design of the Banks’ house is much too grand – which is exactly what writers do. She draws her American collaborators’ attention to cultural differences they might not be aware of. (The makers of Saving Mr. Banks might have learned from this: their recreation of early 20th century Australia is entirely tone-deaf.) It’s insulting to Travers, particularly when set alongside the movie’s adoring treatment of Walt Disney. He’s played by the great American Everyman Tom Hanks with a merry twinkle in his eye; he’s kind to his employees and ready to hand out autographs to anyone who asks. He’s patient with the prickly author. To Disney, however, Travers is a difficult guest whose feelings must be coddled rather than a collaborator he should engage. Travers’ problem is that she’s a collaborator who insists on being treated like one.

In many ways, Mary Poppins the film does improve on the book: the story benefits from a little sweetening. It remains the definitive Julie Andrews performance. Mary Poppins’ vanity and briskness are a perfect fit for Andrews’ own air of self-satisfaction: her perfect enunciation, the calculation of effect that’s so typical of performers in musical theatre. When Andrews’ reflection harmonises with her during “A Spoonful of Sugar”, it’s a perfect moment of self-infatuation. The movie expands upon and satirises the book’s Edwardian world: Glynis Johns’ absent-minded suffragette; David Tomlinson’s pompous self-regard as the man of the house; the hoary old imperialists at the Bank (with Dick Van Dyke at their head, giving a wonderful parody of wheezy eminence). Songs like “Sister Suffragette” (“Though we adore men individually/We agree that as a group, they’re rather stupid”) and “Fidelity Fiduciary Bank” – delightful in themselves – are crammed full of topical references. This contextualises the story in a way Travers never does: perhaps Travers assumed that her audience needed no explanation. (Mary Poppins never explains.) Watching the movie in the Australian suburbs in the late 1980s, though, Disney’s version of Edwardian London seemed almost as peculiar and fabulous as the children’s holiday in the chalk picture.

Other changes are more surprising. Disney’s approach to the material is the opposite to his usual twee, sanitising procedure: he deepens it, introduces notes of darkness and discouragement alongside the songs and the special effects. The only death in Mary Poppins happens off-screen, but there’s a moment very much like an execution: when Tomlinson is called into the Bank to answer for his children’s behaviour. As he walks through the empty city at night, he might be going to the gallows. One by one, his employers strip him of the symbols of his success. Mr. Banks has little time for children; he defines himself by the figure he cuts in the world of money. The film depicts this as a sad limitation; it understands the loneliness inherent in it. It’s a rare children’s movie that extends such empathy to its adult antagonist. He has a sort of breakdown: when he shows up at the house with the repaired kite, there’s something manic, almost unhinged about him. Disney’s victory wasn’t so much overcoming a difficult author with American bonhomie as placing her adventures in a historical context – a satirical vision of late Empire – and supplying them with new emotional amplitude. It’s hard to shake the children’s nightmare vision of London when they flee the Bank, or the way the family closes ranks in its happiness, leaving Mary Poppins to depart quite forgotten. Yul Brynner’s dying message fit right in.