Ten Years After:

Not my cup of tea, I'm sorry to say. Had great problems watching Alvin Lee in the "Woodstock" movie. It goes on and on and on... But I admit he has good technique and can reel off impressive jazz phrasings. And Leo Lyons' moustaches - and bass chops - impressed me too.

Ric Lee on drums played with Stan Webb for a while - like everybody else, I almost added (on album "Roadies Concerto" 1981).
To be fair, I never caught T.Y.A. truly live - perhaps that could have changed my mind.

Lester Bangs of "Creem" magazine did. He waxed it poetically about Alvin in the April '73 issue:

"When he's in full flight Alvin sidles up to the microphone and grins like a moose. He's built like a football player, and his guitar english is in accordance with the image - none of this fey barely-touching stuff for Mr. Lee (unless he wuz touching one of the Bobbettes) - he grits and grinds and bumps and juts, making it clear without overstating his virility that he don't fuck around.
He has a great sense of humour, too - whilst playing 78 RPM ultimo methedrine guitar with one hand, shaking the mike with the other, bouncing stage front in a kind of electric slouch (like a vibrating spring) and singing in the corniest and most blatant ripoff of something resembling an old New Orleans Smiley Lewis vocal style ever heard, he'll swivel his skull and literally leer at the audience with glee at once sly and mindless. Naturally they ate it up. That man ain't no fool."
Mind you: Lester was a T.Y.A. fan! About the group:
"...TYA are in some ways the granddaddies of the whole blooming boogie-bloozup-getdown school of band which has proliferated since they first hit the sets. Savoy Brown copped their riffs in all comradeship, Cactus would be lost without their model, and Foghat would never had existed had TYA not blazed the trail, Alvin hacking away the jungle with a machete..."
Link:
Alvin Lee & Ten Years After: The Official Alvin Lee Web Site