At the end of the song, there is a whole dialogue which is very difficult to understand, but thanks to my new Philips Fidelio X1 headset, I managed to finally decipher the text.
I always thought it was John saying stuff about how Paul McCartney died in a bike accident in 1966 and which was later made infamous with the "Paul is Dead" myth. But careful listening to the remastered CD with a good headset reveals that it is actually part of a scene from William Shakespeare's King Lear.
The excerpt begins at Act IV, Sc vi,II lines 224-25,where the disguised Edgar talks to his estranged and maliciously blinded father the Earl of Gloucester:
Edg: A most poor man, made tame to fortune's blows."
Edgar then kills Oswald the steward of Goneril (who cries out "Slave, thou has't slain me").
Edgar describes the dead Oswald in words heard in the song's coda as a "serviceable villain."
Gloucester asks "What, is he dead?" and Edgar replies "Sit ye down father rest you.