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.
