Place the joint in a large pan over the hob, or burner, and add 7 quarts of dry ginger ale. Bring the pan to the boil then lower the heat slightly so that it keeps bubbling steadily for 4 1/2 hours.
Towards the end of the 4 1/2 hours, preheat the oven to 425 degrees F and begin the glaze.
In a bowl, add 1 cup of chunky ginger preserves. Stir in 2 tablespoons of hot English mustard. Add 1/2 a cup of soft, dark brown sugar and sprinkle in 1/2 a teaspoon of ground cloves.
After 4 1/2 hours, gently lift the ham out of the pan and place on a foil-lined baking tray. Carefully cut away the skin, leaving a thin layer of fat. There is no need to score the surface, simply slap on the glaze and place the tray with the ham into the oven for 20 minutes.
Serve hot or cold.