I think one of the themes of this song is: Tony Blair. Maybe parallels between Blair and other historical figures like Napoleon. The evidence: Tony Blair was the darling of the British left when he got elected, but one event - the alleged lies over the invasion of Iraq - destroyed his image with people of this political view almost overnight. Tony Blair got the keys to Downing Street and this gave him the power to raise seas (like with Polaris missiles) but in the end "People couldn't believe what I'd become" as many thought his drive to push the Iraq invasion through parliament betrayed all of the left's principals. The jerusalem bells line makes me think of the fact that Blair's new job is Middle-East Envoy, and the Roman Cavalry that he recently converted to Catholicism in Rome. I know there are other details in the lyrics that don't fit so well, but this song just really makes me think of Blair and his tarnished reputation (as many on the British left would see it).