"Sex? Drugs? Don't be ridiculous! This is a satire of the ignorance of the bourgeois classes, a spoilt upper class girl is being shown the lives of the proletariat.

"Princess" is obviously a derogatory (sp?) word used to refer to the girl.

"When did you last let your heart decide?" is a reference to the deliberate ignorance, Out-of-sight-out-of-mind mentality... They would never stop and consider the plight of the poorer folk.

"No one to tell you 'No' or where to go or say you're only dreaming", the "princess" can have whatever she wants.

The "endless diamond sky" is the girl finally beginning to realise that all her wealth comes in fact from the workers, "Don't you dare close your eyes" - The working class boy urging her to accept the truth.

"Every moment red-letter" - Red being the colour of socialism, of course."