I think it's a mistake to try to draw references to specific rulers for this song, as it winds up being a mishmash of unrelated themes/people. For instance, if the second line really did refer to Canute, there's the problem that Canute was never overthrown. So, there is no relation between that line and the line immediately following. Similarly, if we are going to look for a parallel for "head on a silver plate," the only figure available is John the Baptist, who could hardly be called a worldly leader. And would be more in line with the revolutionaries. (Which would not include the American revolution, as the American "revolutionaries" never threatened the existence of the British crown) But if you want to play, "I used to roll the dice" could refer either to Julius Caesar as he crossed the Rubicon ("iacta alea est"), or the legendary gambler John Montagu, Earl of Sandwhich ;) However, listening to the song multiple times, it is Roman Cavalry, not Calvary (in which case, the adjective Roman would create a rather odd construction). The typo, I believe, is that there should be a comma after Cavalry, as again "Roman Cavalry choirs" doesn't make much sense. Yet, if you see them as three different elements: Jerusalem bells ringing, Roman Cavalry, choirs singing, it sounds like a celebration for a victorious army, something you'd expect the singer to relate as he describes "when I ruled the world." In the end, I see this as a general tale of a man who gained power/fame/wealth through forces beyond his control (wicked and wild wind), grew arrogant in his good fortune (seas would rise when I gave the world), and so had it all collapse around him (pillars of salt, pillars of sand). The theme could have been ripped right out of Machiavelli's The Prince.