Doesn't African Blackwood come under the rosewood family, which is controlled under CITES appendix 2.
George, your definition of "exotics" could include pine because it is imported from a number of countries - Canada, Scandinavian countries etc. Also Oak, which is imported from various countries, Ash etc etc.
A separate question - most if not all the UK suppliers of turning wood claim to source their timber from "managed resources". Do we take that at face value? Should we expect more of them in terms of ethics by only sourcing wood which is from sustainable sources? This would exclude those part worked blanks done to circumvent local restrictions and timber from trees which could never be described as sustainable because they take so long to grow!
Should we follow the lead of food producer and advertise "wood miles" for the things we make and sell?