I've recently discovered Sister Rosetta Tharpe, a blues and gospel singer with a long career. Great voice, excellent attack on guitar (a Gibson SG with three (three!) humbuckers no less) and that indefinable ability to come out of the speakers and grab the listener by the throat.
Check out this YouTube clip especially the solo starting at 1:25
Performed several years before the Bluesbreakers album and makes Eric "God" Clapton look like a simpering lily-white school-boy.