Mary Poppins by Disney, is not the P.L. Travers version. In the original books, the Banks children live in a dark, sugarless world which is brightened by Mary only inasmuch as she shows them a different side of life. A magical side of a world where infants are forced to forget their union with the universe by the rigours of our society.
Recently I read that within 15 years the true London or "cockney" accent will be extinct. Immigration, the influence of film & music and the "Americanisation" of society will leave the Pearly Kings & Queens of the East End and the true cockney sparrows who were born within the sound of Bow Bells as dead as a Dodo.