http://youtu.be/dJeBvNuYPMM
Prog .........Really ??
Early Genesis , Yes , Jethro Tull and the like .......but not Rainbow.You also include Deep Purple . Not even Jon Lord's dabblings in Purple evoke any kind of relationship to prog to me .And when Hughes and Coverdale joined , they changed it to a more blues/soul vibe , hence encouraging Blackmore to leave and form Rainbow. Back in the day Rainbow could be found under either Heavy Rock or Contemporary Rock.
Interesting series on Sky Arts 1 called 'Metal Evolution ' sites Rainbow (especially the song Stargazer ) as the early incarnation of what is now been dubbed European 'Power Metal'. Songs about Vikings ,Dragons and mythology normally sung by Nordic and Germanic bands with screaming falsetto and uber fast twiddly bits on the fretboard. Sort of Rob Halford meets Yngwie Malmsteen .
All in the ear of the beholder of course.
RJD RIP. (2 years this coming Wednesday).