Check the weight of the gammon and calculate the, allowing 40 minutes per kg, plus 40 minutes. Place in a stockpot or large saucepan big enough to hold the joint and whole vegetables.
Add the ginger, cinnamon, cardamom and cider. Bring to the boil, skimming off any scum from the surface. Reduce the heat, cover and simmer gently for the calculated time: 1½ hours for a 1.2kg joint.
After about 40 minutes of cooking, prepare the fruit. Cut each apple into 8 wedges and core them. Quarter and core the pears. Add the fruit to the simmering cider and poach for 5–10 minutes or until just tender. Use a draining spoon to transfer the fruit to a dish. Mix the marmalade with 1 tbsp of the cooking liquid, add to the fruit and toss to glaze. Set aside.
About 20 minutes before the gammon has finished cooking, add the whole turnips and carrots to the pan. When the gammon is ready, use a meat fork and spatula to lift it from the pan. Set aside, loosely covered with foil, to rest. Add the corn to the vegetables in the pan and cook for a final 5 minutes. Drain the vegetables.
Serve the gammon thickly sliced on a platter with the vegetables and cooled glazed fruit arranged around it.