unmanned transport - "The USA were flying Mach 3 plus aircraft
(SR71, XB70, X15, Apollo, Shuttle)."
You from the USA by any chance? The a/c you list, unless I am mistaken do not carry 100 people at Mach2 for a few hours. In any case IF the USA develops a supersonic transport will there be an orchestrated series of demonstartions to keep it out of US airspace until all orders have dried up? I did not think so. I am proud that Britain built Concorde and she is still the ONLY supersonic passenger a/c the world has seen.