Subject to the provisions of regulations 323(2)(a) and 327, the driver of a vehicle on a public road who intends to turn to the left or move to the left shall, before reaching the point at which he or she intends to turn or move to the left, extend his or her right arm sideward from the shoulder with the forearm in a vertical and downward position and move his or her forearm in a circular anti-clockwise motion: Provided that in the case of a driver of a tractor, a two-wheel vehicle or an animal drawn vehicle, such driver may, in lieu of the hand signal aforesaid, extend his or her left arm and hand sideward from the shoulder and fully horizontal to the road with the palm of the hand turned to the front.