The pilot, who was conducting a VFR charter flight, advised that the destination conditions were fine with a north-westerly wind of 15 to 20 knots. Runway 26, the runway in use, is 983 metres long with 0.5 percent downhill slope at the western end, and has a loose gravel surface. During the approach the pilot selected 10 degrees of flap, but further flap selections were unsuccessful. The approach was then continued using the 10 degree flap configuration crossing the runway threshold, 80-100 feet above ground level, at 80 knots. While flaring for the landing the pilot believed that the wind veered, to a tailwind component and caused the aircraft to float further than anticipated. The aircraft touched down well into the runway and the pilot applied maximum braking, but traction was poor. The pilot then pushed forward on the control column in the belief that this would prevent the aircraft from becoming airborne, and improve the nosewheel steering. With the subsequent reduction of weight on the mainwheels, and assisted by a flap setting producing lift, the aircraft would have "wheelbarrowed" along the remainder of the airstrip, which was now downhill. With approximately 100-150 metres of runway remaining, the pilot realised that there was now insufficient runway length available in which to stop or attempt a go-around. The aircraft crossed the end of the runway at about 30 knots and entered a ditch, located approximately 50 metres further on, causing the nose leg to collapse. The aircraft came to rest 70 metres from the end of the runway on its propeller and left hand wingtip. This accident was not the subject of an on-scene investigation.