Wikipedia has an article about Revisionism in the Marxist tradition. Here. While I generally distrust Wikipedia, I do generally think this makes sense in that the attribution of Revisionism as a whole goes to Eduard Bernstein.(and Jean Jaures) Here's what it says:
who sought to revise Karl Marx's ideas about the transition to socialism and claimed that a revolution through force was not necessary to achieve a socialist society. The views of Bernstein and Jaurès gave rise to reformist theory, which asserts that socialism can be achieved through gradual peaceful reforms from within a capitalist system.
The image caption on the right says the following:
Eduard Bernstein, originator of the original Revisionism.
I found this to be intriguing, as well as the whole timing, considering that (As I've previously noted) one of the major precursors to Fabian Socialism in Britain(and in the US I might add) is Henry George's Book. In the late 1800's. Also, this is right around the time that progressivism rears it's ugly little head. Late 1800's, early 1900's. And how Bernstein ties into this is incredible. He wrote the book on Evolutionary Socialism, in 1899. I think this may be it's English translation.
Now think about that for a second. Does not "Evolutionary Socialism" perfectly describe Fabianism? And while we're at it, does it not also in large part describe progressivism? I can't help but see that all these puzzle pieces fit together perfectly.