The aircraft was on a flight from Carlisle to Coleraine, Northern Ireland with the pilot and three passengers on board. Following an uneventful flight and approach to land, the aircraft touched down on the grass strip. The pilot advised that the weather was calm and the grass was still wet with morning dew and he was aware that this would have a detrimental effect on braking distance. The left mainwheel touched first, followed by the right mainwheel and then the nose wheel. The pilot realised that the aircraft was tracking to the left, rather than along the runway. He progressively applied more rudder and right brake, but by this time the left wheel had entered the long grass at the edge of the runway. The additional drag pulled the aircraft further to the left and it ran through a wire fence, before coming to rest in an adjacent field. The aircraft operator advised that no pre-accident defects were identified with the aircraft’s landing gear.