In the comments regarding yesterday's item, Joe described "Revolution" as sort of a pastiche of the Beatles' early influences, noting, "The slow version is Chess records on the nod with doo-wop backing vocals." Joe is probably aware of this, but those doo-wop vocals were originally on the fast version as well.
You can tell this because at some point between when the single version of "Revolution" was cut, on July 12, 1968, and when it was released, on August 28, 1968, the Beatles made a video for the song. On it, you can clearly see Paul and George, although miming to a backing track, stepping forward to the microphone and mouthing the words "ah-om, shoo-be-doo-wop," although no sound comes out. Obviously, they put the backing vocals on the original record and made the video expecting them to still be there, then someone wiped them off before the single was released.
You can see that video here, if you so choose. The original video, with the backing vocals restored, surfaced on the Beatles Anthology DVD, and it sounded great. The shoo-be-doo-wops made even more explicit the connection between the Beatles' roots in Fifties rock & roll and the late-Sixties sensibility of the lyrics and the screaming guitar. Kind of like how Amy Winehouse's "Rehab" connected the Motown sound with the moral issues of the Aughts.
(Incidentally, I meant to mention this earlier, but the first disc of the Blue Album, which traces from "Strawberry Fields Forever"/"Penny Lane" through Sgt. Pepper and up to "Hey Jude"/"Revolution," would be by far the greatest album ever made if it had been issued by its lonesome. The only real weak track on there is "Magical Mystery Tour," and most of the songs on there are stone classics, including five of Rolling Stone's 500 Greatest Songs, and that doesn't even include "Revolution." Which brings up the question: How is "Revolution" not one of the 500 Greatest Songs? [Even more incidentally, the line "When you go carrying pictures of Chairman Mao, you ain't gonna make it with anyone anyhow" carries special resonance for anyone who has visited the offices of Rolling Stone.])
Anyway, let's have a listen: