Now I am even more baffled.

I just re-ran the process with the moved bones only skeleton......one which ran perfectly yesterday ..and had it fail in exactly the same way. Now...I knew this was not likely to be a 'random' thing, so I did a bit of head scratching, and realised that I had previousely commented out the scale entry in descr_skeleton and put it BACK in to try something else. Took it back out...and as if by magic...it worked again.

So... one element that was screwing things up was scaling. Not completely the solution, because all the previous tests were done on a 1,1,1 scale, and not everything worked.... but I have found a way of deliberately creating the effect I have seen... and I did it by scaling the skeletons as well as the mesh... which seemed strange...but not so if the scaling factor in the skeleton was applied to something that was already scaled... if you see what I mean!


Anyway....

I have a horse which has gained some bones for a chariot, but lost it's tail in the process. Small price to pay! Now I just need to animate the former tail bones to make the chariot and wheels work properly!