Revelation was deliberately left out because it was seen as being too 
open to misinterpretation, especially in a politically subversive 
manner.  Anglicans were particularly concerned that Babylon would be 
equated with monarchy by more radical Protestants.  I think it's 
O'Donovan that discusses all this in one of his books.  A good reminder 
that politics have always been involved in devising lectionaries!!

Mark+