After flying in the local area for a time, the pilot entered a long straight-in final approach for the easterly strip he had used for take-off. From a distance he observed that the wind was a light southerly. Following a slight bounce on touchdown, braking was initiated but the aircraft seemed to be travelling faster than normal. The pilot, believing that he had landed with a tail-wind, turned the aircraft to the north-east to increase the landing roll available. The aircraft overran the area into a fence and firebreak. The approach speed used was 12 knots faster than that recommended in the landing chart. The bounced landing, slippery grass surface and use of other than maximum braking increased the stopping distance required. The direction of turn chosen by the pilot to increase his stopping distance was downhill and with a tailwind component. The presence of telephone lines at the end of the strip precluded a go-around.