After starting his career as a much-in-demand session pianist (he put together Joe Cocker’s US band), he spent the ’70s as a rockabilly star in his own right. (Elton John was once his opening act.) “He wore a cocked top hat, and with salt-and-pepper hair past his shoulders and a beard that reached his chest, created an inscrutable image that was equal parts shaman, tent revival preacher and cosmic ringmaster.”