Keep in mind that to operate the brake, the reins would need to be in one hand so a hand would be free, the same with a whip. Both being very important in coaching For pairs I have found using a "bridge" works best for me in CDE. I am sure others can describe it better but the reins are held in the left hand and the right rein is pulled out to make a small "bridge" or short distance between the hands so they can be held about the same distance from the bit. I believe that the need to operate the brake and the custom of having the reins in the left hand was the reason the whip sat on the right in England, And thus why they passed to the right in England and thus why the English drive on the left side. French coaches were driven by post boys sitting on the horse. They mounted on the left as riders do, and thus passed on the left and as result the French drive today on the right. Douglas Kemmerer Middleburg, VA