A anonymous ground witness observed the Cessna 206 overfly the windsock before commencing an approach to land on the north westerly strip. Most of the time there appeared to be a 20 knot crosswind from the left, but occasionally the wind swung so that there was a tailwind component. The witness advised that after touching down about 100 metres into the 490 metre strip, the aircraft bounced once and floated until almost two thirds down the strip where, after touching down again, the brakes appeared to be applied. Shortly after the brakes were applied, the wheels appeared to lock causing loss of directional control. The aircraft departed the centreline to the right, struck bushes about 70 metres from the end of the strip and overturned. According to the pilot, he performed a normal short field approach and landing uphill on the 310 degree strip with the wind 220 degrees gusting from 10 to 15 knots and the aircraft touched down near the threshold without bouncing or floating. During the landing roll the pilot believed that the wind changed to provide a significant tailwind component which made the aircraft difficult to slow down and control. The pilot did not attempt a go-around.