Most iconic British rock clubs, including the Cavern, were jazz clubs. Musicians always went to jazz clubs. Pop groups were put on at the Cavern at lunchtime to subsidise the jazz club. This is why Ringo and the other British drummers of note were so good. Because they LISTENED to the jazz drummers and we were able to ask questions. A legendary Liverpool drum teacher was Red Carter. everyone seemed to go to Red at some time or other.