Preheat oven to 175°C (or 155°C fan bake). Remove ham from fridge.
Place cider (or alternatively, use same amount apple, orange or pineapple juice), Chelsea Dark Cane Sugar and butter in a small pot on medium heat. Bring to a boil for reduce for 3-5 minutes or until slightly thickened. Set aside to cool
Pat ham dry. With a knife, carefully loosen skin from ham being careful to leave the layer of white fat as this keeps ham moist (see image). Slip your fingertips under loosened skin and pull to remove and discard. If you have the knuckle end of ham, wrap foil around hock to stop it burning.
Hold the ham firmly with one hand, and with the other hand, take a sharp knife and make diagonal cuts about 1/4-inch deep across the surface of the ham. Rotate the ham and repeat the diagonal cuts in the opposite direction.
Place ham in a lined roasting dish (fat side up) and brush with half of the glaze. Pour water measure in base of dish, then cover with foil. Bake for 30 minutes, then re-glaze ham. Bake a further 40-45 minutes. Rotate ham to ensure even cooking. Add 1/2 cup water if glaze starts to burn. Remove ham from oven and set aside, covered with foil and a tea towel to keep warm and rest, until ready to serve.
Thinly slice ham just before serving.