It is so wrong to call Elvis Costello or The Clash "classic rock" ... The Man was essentially (until he became the preening pop queen he was originally out to destroy) New Wave, and the point of New Wave was to kill dead the bloated dinosaur rock represented by Led Zep, E.L.P., etc. I believe it was Esquire magazine that called Elvis' first three albums (paraphrased) the most furious album trilogy in the history of rock 'n' roll.
The "agenda" of The Clash (originally closer in sound to the Sex Pistols) and E.C. (one in spirit with them from the beginning) was summarized by Johnny Rotten's famous t-shirt that read "I Hate Pink Floyd".
Somewhere along the way, though, Elvis lost his little black book ...
Yours,
Jeff