This might be a stupid question, but what did 'stormtrooper' refer to before Star Wars? When I first saw a song with the subtitle Stormtroopers In Stilettos I assumed it was a Star Wars reference, not knowing that Star Wars was made a few years after Sheer Heart Attack :P
well, you're not far off...
Lucas was heavily influenced when it came to the evil Galactic Empire from the Nazis...as you can notice esp. in the dark costumes in the scenes inside the battleships
these days the name Storm Troopers is immediately related to Lucas' galactic saga, but in reality its basic connotation is the SA (short for Sturmabteilung) - or the Brownshirts, a semi-military corps which evolved from Hitler's bodyguard, which grew out of control and was neutralized in 1934...later on the SA were "replaced" by the SS, which most have heard of, one of the most inhuman corps to have walked the Earth...
Stormtrooper is actually the name given to "specialist" soldiers, in WWI, i.e. commando
"Stormtrooper" is from the German "sturm", meaning both "storm" and "assault" (although the latter was originally sturmangriff, literally "storm attack"). Lucas got it from the SA, or Sturmabteilung (roughly translated, "assault unit"), the armed nazi streetfighters in the early days of Hitler's regime.
So, before about 1925, "stormtroopers" meant soldiers specifically trained for attacking enemy positions (usually meaning they were better armed and possibly carried body armor), after that it began to mean "nazi paramilitary", which it remained until Star Wars.
Brian May was referring to the pulp image popularized in the 1960s and 1970s of female nazi disciplinarians wearing SS uniforms, catering to sexual fetishism.