The pilot was ferrying the aircraft to Killara Station for the owner. He had checked the condition of the strip prior to departure and was advised to land on a road near the homestead as the main strip was unserviceable. The pilot reported that on arrival he made two low approaches to confirm that the road was suitable and then made a third approach for the landing. There was no windsock visible; however, a windmill indicated that the wind was a crosswind from the right. At about 25 ft on final approach the aircraft started to drift away from the centreline of the road. The pilot was unhappy with the approach and decided to go-around. He opened the throttle; however, before the engine could respond the aircraft descended rapidly and landed heavily on the edge of the road. The aircraft ran off the road into trees, the nosewheel dug in and it overturned. It was reported that there were no unusual atmospheric conditions present at the time of the accident. It is probable that the sudden descent occurred because the pilot inadvertently allowed the airspeed to reduce to the stall speed during the attempted go-around.