Combine the ham with the onions, apples, ginger beer, garlic, Worcester sauce and 1 dessertspoon mustard. Marinate overnight. (You might have to weigh it down with a plate with a tin on top to keep the joint immersed!)
Preheat the oven to 170 C / Gas 3. Place the ham joint in a roasting tin along all marinade ingredients. Cover with foil.
Cook the ham around 1 1/2 hours or until the meat is cooked through and the juices run clear when a skewer is inserted. If you like you can combine the optional glaze ingredients and spread on the ham and roast in a high oven for about 10-15 minutes at the end.
Better to get a joint without bone, and note that smoked gives a different flavour! The gravy can be reduced and used alongside the ham if desired. Hope you enjoy!