Bring to the boil, then discard the water and start again with fresh water ... burning). Roast for about 30 minutes, coating with the remaining glaze halfway through, until the ham is sticky ...
Drain and discard the cooking water. Once the ham is ready to cook, put the joint into a large pan, cover with fresh cold water and add the leeks, onion, carrot, peppercorns, and bay leaves.