In a piece for the New York Times, Professor Daniel Pollack-Pelzner criticises one of the film's iconic moments, when Mary Poppins joins Dick Van Dyke's Bert to dance on a rooftop for the classic song Step in Time.
He writes: "When the magical nanny (played by Julie Andrews) accompanies her young charges, Michael and Jane Banks, up their chimney, her face gets covered in soot, but instead of wiping it off, she gamely powders her nose and cheeks even blacker."
"This might seem like an innocuous comic scene if Travers’s novels didn’t associate chimney sweeps’ blackened faces with racial caricature. “Don’t touch me, you black heathen,” a housemaid screams in “Mary Poppins Opens the Door” (1943)."
"When the dark figures of the chimney sweeps Step in Time on a roof, a naval buffoon, Admiral Boom shouts, “We’re being attacked by Hottentots!” and orders his cannon to be fired at the “cheeky devils”.

"We’re in on the joke, such as it is: These aren’t really black Africans; they’re grinning white dancers in blackface. It’s a parody of black menace; it’s even posted on a white nationalist website as evidence of the film’s racial hierarchy."
Fans were divided over the professor's remarks. 
One wrote online: "I think this is a reach.  She was friends with a chimney sweep.  When she went out and danced with him she got soot on her face if I recall this correctly."
Another wrote: "Mary Poppins wasn’t flirting with black face! It was soot in their faces from being a chimney!!!"
A third said: "This is a candidate for the stupidest New York Times article of all time."
However others agreed with some of the points raised.
Michael Schulman, ,a writer for the New Yorker said: "This made me think about class, too - how Mary Poppins, a posh domestic, scrambles the class divide and introduces Jane & Michael to the much more fun world of pleb chimney sweeps. Further scrambled in the sequel when the Bankses are also in the poorhouse."
Author Mr Pollack-Pelzner posted online after his article was published: "The chief reason I wrote this article was the hope that a Disney exec would read it, take another look at the forthcoming Dumbo remake, and ask if there was anything just a little bit racist they might want to rethink before it hits the big screen.
"Here’s one thing I’ve learned about the alt-right, after I wrote this article and received a zillion hate messages in response: they sure like Mary Poppins!"