JETHRO TULL
I have never been quite sure what Jethro Tull were - rock, folk, prog. guess they were a bit of all three. They had a rock power to their sound at times, but also the folky interjections of Ian Anderson's folky flute were integral to their music. Furthermore, "concept" albums like Thick As A Brick and A Passion Play were as prog as it gets. Anyway, it's time to stand on one leg and play that air flute....