Absolutely, there's such a thing as British blues. Like most white guitar players of a certain age, it took guys from across the pond to hip me to this great music that was in my own back yard (so to speak), as the only black artists I heard on mainstream Top-40 radio in the early '60's were more soul- and doo-wop-oriented (Chuck Berry and Little Richard notwithstanding, but by the early '60's they weren't getting as much airplay on white radio). I loved (and still do) that stuff too, but the first blues that I actually recognized as such was by the Rolling Stones, probably "Spider And The Fly". The English guys weren't shy about telling us where they got this stuff from, and pretty soon I was finding out about Muddy Waters, Howling Wolf, B B King, John Lee Hooker--all the real stuff. Even the black radio stations weren't playing blues in the '60's, so the Brits were giving us white kids a real education regarding our roots that we didn't know about. It took a white guy from Chicago, Mike Bloomfield, to show me that blues guitar could be a way for me to shine without having to be the lead singer, and when I heard Clapton (Cream first, then the Bluesbreakers LP--I really got it backwards!) I had a direction to follow. The British guys had a little different approach than the older American blues guys--more aggressive, at least on record, and a little more eclectic than the guys who influenced them. The B B King influence is certainly apparent in Eric Clapton's blues playing, as well as Albert King and Otis Rush, but he took it to a different place. I'm glad we got underground rock FM radio (originated in my hometown, San Francisco) in '67--they played a lot of blues, as well as local Bay Area rock, Indian music, and even a bit of jazz; a real freewheeling approach. I miss that stuff!
British blues eventually got mixed into what became heavy metal, but they definitely took a unique approach to what had been pretty much an American style of music with African roots. Now it's just universal--everybody gets the blues! From the cantor in the synagogue when I was growing up, to Ravi Shankar bending notes on the sitar, it's all a way to express emotion, and we all do that in one way or another. I've heard Indian sitar players do stuff that's reminiscent of blues guitar, sometimes like bluegrass dobro, but I don't think the Indian guys were listening to B B King and Bill Monroe! It's got to be that human thing...