Clearly, the order imposed by privileged men will be sabotaged by rebellion — specifically the rebellion of women assisted by children and by men of the underclass.
It’s no surprise, then, that the abrupt departure of yet another nanny disrupts the Banks’ rigidly conventional household. Seeking a stern replacement, Mr. Banks is instead outfaced by Mary Poppins, a pert young governess who flouts her prescribed submissive role by refusing to give references and demanding the family submit to a probationary period.
Mary proceeds to introduce the children to members of a lively underclass, including street peddlers, carnival workers, penguin waiters, her decidedly odd Uncle Albert, and of course Burt (Dick van Dyke sporting a hammy accent), the raffish charmer who, between his makeshift enterprises, accompanies Mary on her many secret adventures. Unlike Mrs. Banks’ flighty clamor for equal rights (which is silenced instantly by her husband’s presence), Mary’s subversive influence begins to color the attitudes of the entire household, and even infiltrates Mr. Banks’ place of work.
Tellingly, though Mary seems at first to overthrow the prevailing power structure, she — and her subversive influence — vanishes at film’s end. After her disappearance, the power structures of the privileged are tempered by familial affection, but otherwise they remain intact and authoritative.