A close friend of mine claims (and has for the past 25-odd years) to have jammed with Adrian and Nicko while on vacation in the Bahamas once in the 90's. My friend played bass, and when they started, Adrian leaned over and mumbled, "blues in C" and just went from there.
He's a close, close friend, and while he's prone to boasting, he's not one to make stories out of whole cloth. I've not seen any photos but I tend to believe him. I do know he said Adrian was on another level entirely in terms of playing (and my friend is no slouch; he's played 100's of shows and even cut a record back in the 90's.)