It’s only now they are isolating the drum tracks and highlighting songs where Charlie drove the whole thing that I realise what a good drummer he was (not that I am well qualified to judge). RIP.
He was primarily a jazz and rhythm and blues player before he ventured on to the rock scene. He would've learnt great techniques and playing difficult time signatures with that grounding. Rock music tends to be straight forward 4/4 more often than not. One of my mate's was Watts painter and decorator. He said his apartment near Battersea bridge was like a shrine to jazz legend Charlie Parker.

