The reference is to The West Wing, episode 7, series 2, The Portland Trip:
Sam:Oratory should raise your heart rate. Oratory should blow the doors off the place. We should be talking about not being satisfied with past solutions, we should be talking about a permanent revolution.
Toby:Where have I heard that?
Sam:I got it from a book.
Toby: What book?
Sam:The Little Red Book.
Toby:You think we should quote Mao Tse-Tung?
Sam:We do need a permanent revolution.
Toby:Still, I think we’ll stay away from quoting Communists.
Sam:You think a Communist never wrote an elegant phrase?
Sam:How do you think they got everybody to be Communists?
So that’s where John McDonnell got the idea!
Those who believe great oratory is not dead will take comfort from Chris Bryant giving Chris Grayling (and others) a right doing-over: