Gargoyle,I'm a big fan of Phil Keaggy. I believe the story you are reffering to has nothing to do with Clapton. The story that I've heard (over and over) was that it was Hendrix. I guess Johny Carson asked Hendrix what it was like being the best guitarist in the world and Henrix said you'd have to ask Phil Keaggy.
I never believed the story for a number of reasons (one being that he has never confirmed this) but it is appearently documented on an old episode of Johny Carson.