Preheat oven to gas 4, 180ºC, fan 160ºC. Place gammon in a large saucepan with a lid. Pour over the lemonade (liquid should just cover the joint). Bring to the boil on the hob and then lower the heat to simmer for calculated cooking time.
30 minutes before the end of cooking time place the Pimms into a small saucepan, add the apple sauce and bring to the boil. Lower the heat and simmer for about 10-15 minutes until mixture has reduced slightly.
15 minutes before the end of the gammon cooking time remove joint. Carefully remove fat and score the remaining layer into diamonds or small squares. Spoon over the glaze/sauce and place in a roasting tin in the oven for 10-15 minutes until joint is golden brown.
Serve sliced, either hot or cold, spoon over any remaining juices and serve with an apple, cucumber and mint salad and thickly sliced crusty bread.