i've made this comment in another thread but including Led Zeppelin would be to rewrite musical history.
In their time they were never regarded as a progressive rock band but were termed 'heavy blues'.
The only song which Zeppelin ever openly admitted to being prog-influenced was 'The Song Remains The Same' which Jimmy knowingly constructed as an excercise in prog rock-ism.
I adore Zeppelin, have done since I first heard them, in 1979 when I was 13, I have everything they recorded inncluding box sets, blah blah blah but they were not then prog, nor will they ever be.
In fact, in a bid to halt all these tiresome polls, here's my earlier post:
With reference to my earlier post about the change in demographics on the site and the possible need to create a sub-forum for 'bands related to prog'.
There are now threads on the main discussion board for Chicken Shack, Artcane, Quatermass, Queen (regarding Queen II) and a query about Autograph's inlcusion on the site. That's just on page one of the main discussions area.
On page two we get Man, Horslips, Wishbone Ash and a few others.
We've had endless, pointless discussions about ELO, Led Zeppelin etc etc etc.
The sheer proliferation of threads suggesting bands for the site is proof positive to me that an awful lot of member do not have an inkling of even what the 'classic' early 70s definition of progressive rock is.
Even if you broaden the scope of the definition and the site's ability to induct marginal bands - there is simply no way on God's green earth that a case can be made for Zeppelin, ELO, 10cc, Roxy Music etc etc.
If 'progressive rock' as a tag was applied largely by music journalists to try and encompass a loose musical movement of the late 60s then it was a tag (however imperfect) that was never, ever applied (as far as I know) to any of the above groups. Zepp were classed as a 'heavy blues band' ELO as pure pop, 10cc likewise, Roxy as more akin to Bowie and Lou Reed and glam than prog rock.
I am no diehard adherent to the flat-earth notion that any change must be resisted but like, I think it was Fitz, it is just not correct to trawl back through time and adjust the parameters to suit personal taste. I adore Zep and have done since I was a teenager, but they were never progressive rock and they won't suddenly become so because someone constantly bleats for their inclusion.
I applauded the inclusion of Radiohead because I believe they fulfill the criteria of being a prog rock band. I have no objection to objectively viewing a modern band's career (Talk Talk, David Sylvian, Radiohead) and deciding that their allegiances, influences, output and progress lead to the conclusion that here's a modern prog band. That's fine. And merited.
Merited because few mainstream music journalists use the term prog rock these days, it's simply fallen out of fashion. Instead they label what we might see as prog tendencies as something else - there are hundreds of ridiculous catch-alls that are applied.
But while those sort of judgment calls are necessary with modern music (to which the term prog is hardly ever applied in the music media - though, strangely, it consistently has been to Radiohead) it is the silliest kind of cultural relativism to stretch back through time and say 10cc are prog.
Just because someone listens to Genesis and 10cc and sees sonic paralells in terms of production values, keyboard sounds of the 70s etc does not mean that band is suddenly prog. They were not then, and they are not now.
Broaden the definition by all means, but do not rewrite popular music history.