With all the crazy stuff on the internet, a “Mary Poppins” fan theory could easily be something quite atrocious.
In the original movie, Julie Andrews plays Mary Poppins, a magical nanny who takes the Banks kids, Michael and Jane, on wild adventures.
The author of the Mary Poppins books, P.L.
In the movie, it appears Bert has some sort of a past with Mary.
Blunt is around the same age Andrews was when playing Mary.