The first prog album ever?????

I know we've discussed this in the Shoutbox but I don't think it's been in the forums before (if I'm wrong forgive me).

There are (obviously) different views on this. This months Classic Rock magazine has an article on this and I was interested to note that The Beatles got mentioned a lot with "Revolver" and "Sgt. Pepper". What do you think of that? Personally if The Beatles could ever be classed as Progressive I'd plump for "Rubber soul" being in there too.

Someone even mentioned Beethoven's "Eroica" symphony (No. 3). I can see what they mean in a way. That really blew the lid off Symphony writing in it's day and could have been classed as Progressive at the time.

What, then, do you all think could be classed as the "First" Prog Rock album?

Taking "Established" bands I'd go for "Days of Future Past" by The Moody Blues - 1967.

Anyone got any more suggestions? Flame on!!!!!!!