It was a low cloud day but dry had been mist wet for previous few days. Surface was thin mud in spots good footing elsewhere. Walk that I was doing 3 times a week a one hour 3 and a half mile loop. Just on final descent to bream down fort, when feet slipped out from underneath scrabbled to stay up an one ankle turned heard the break went to floor fast and tried to stay still. As only a short walk I didn’t have any emergency stuff with me and had left phone with misses in car at base of hill but she knew route and time expected. Most people not walking over top of hills just along path could get their attention they kept just waving back and shouting hello. Had to wait about 15 mins till somebody came over the top to start a rescue.