Actually, Elwood, I always thought Led Zepplin's "Since I've Been Loving You" was a pretty great blues song in my younger days. And since you've mentioned British blues, how about "Lazy" by Deep Purple (Machine Head album). I don't know if they got it from the tradition or just made it up.

LAZY

You're lazy, just stay in bed (2x) Don't want no money, you don't want no bread.

If you're drowning, don't clutch no straw (2x) Don't wanna live, don't wanna try no more.