The only session player in the entire history of the Beatles, of course other than George Martin, was the mystery guitar player on "While My Guitar Gently Weeps." It was Eric Clapton. Why? Because at that time, no guitar player was capable of delivering what the song needed, obviously according to George Harrison. That was a great distorted tone, lyrical string bending guitar with Clapton's signature vibrato. Sure, anyone can play it now. Then it was revolutionary.