So we see Socialism and Liberalism united in accomplishing changes in legislation and ancient institutions - changes that are revolutionary in character and will be far-reaching in results. It is not the red revolutionary Socialism of Marx; it is the practical British Socialism of amelioration. "This practical, constitutional, evolutionary Socialism," a chronicler of the Fabians calls it. It would have to be practical to appeal to the British voter, constitutional to lure the British statesman, and evolutionary to satisfy the British philosopher
Now, while I cannot for sure determine Orth's position and where he is coming from, here is what Edward R Pease wrote by his own hand in "The History of the Fabian Society":
The revolt came from England in the person of Edward Bernstein, who, exiled by Bismarck, took refuge in London, and was for years intimately acquainted with the Fabian Society and its leaders. Soon after his return to Germany he published in 1899 a volume criticising Marxism, and thence grew up the Revisionist movement for free thought in Socialism which has attracted all the younger men, and before the war had virtually, if not actually, obtained control over the Social Democratic Party.
Footnote 45 is the key here. After spending all those years with the Fabians, Bernstein then published "Evolutionary Socialism". So in this regard Orth's quoting of Pease is entirely in context. Here is footnote 45:
 Published in English by the Independent Labour Party in 1909 as "Evolutionary Socialism."
So then that's how it shall be. They are evolutionary socialists, not revolutionary socialists. This is an important distinction to make and knowledge to grasp. The first thing that pops into my head is the words of James Madison:
I believe there are more instances of the abridgement of freedom of the people by gradual and silent encroachments by those in power than by violent and sudden usurpations.
So then it's settled. Progressives and Fabians - the evolutionaries - are a greater threat to liberty than are communists - the revolutionaries. I know Madison has my complete trust. How about you?