The story is that Ginger Baker got Jack fired from GBO. Don't know if it's actually been confirmed by either of them, but there was a lot of hostility between them and Jack left.
If I remember correctly, there are some Graham Bond cuts that are a bit more jazzy with Jack Bruce on an upright and Ginger Baker really working that small kit. Particularly a lot of real old school snare and high hat work......very different from the Ginger Baker multi tom tom stuff we are familiar with. I haven't heard any of that stuff since pre 1970 so the memory may be a bit fogged Rick