I strongly suspect he's been driven before. First of all, he's in general sweet, well-mannered and well-broken, even pretty broke under saddle. IME, most small ponies are started by driving because of the lack of suitable riders.
So I put harness on him for the first time today, and the first clue was that he accepted the crupper with out turning a hair. When I first ground drove him, I picked up the reins and whip and asked him to walk on; he turned by keeping his body straight and crossing over as a horse in shafts will. Highly suspicious.
He was dead solid perfect ground driving. Walk, trot, halt, back in both directions and simple turns, perfect, no problem.
I then hitched a plastic tobaggon to the ends of the traces and had him drag it while ground driving; again, no problem.
Then I had my daughter sit in the tobaggon. He had a little trouble starting off pulling the weight from a standstill, but other than that, was fine. Again, since he could feel the weight on the traces, he would hold his body straight and cross over, rather than bend when he turned.
I am tempted just to hitch him to the cart tomorrow; but prudence prevails. I had my husband make a PVC you the same size as the shafts; I will add that to his ground driving ensemble tomorrow.
What do you think? Pony prodigy or driven before?