"As children some sixty-five years ago, my sisters and I read an actual Mary Poppins book. The title character, as illustrated, was not at all physically beautiful; and though she genuinely cared about the Banks children, she was not so gushing or adventurous as in the movies."
Copper, readers shouldn't go by illustrations in these kind of books to determine what a character looks like. They should go by the descriptions in the text.
"I would imagine that Marry Popppins book is written for an British audience, which has different sensibilities then an American audience."
wonderlings, the Mary Poppins series started in the 1930s. Two kids' book series that were popular around that time in America were "The Nancy Drew" Series and the "Little House on the Prairie" series. Now of course the British audience did then and likely still does have different sensibilities, but since I haven't read those series, would anyone say those main characters were described as physically beautiful? Do not count the pictures.