Place the gammon joint into a large saucepan on the hob.
Cover the joint with water, bay leaves, peppercorns and thyme.
Peel the rind from the orange and add to the pot (try to make sure when you do this you don't have any pith on the rind.)
Juice the orange and add this to the ware before turning on to a moderate heat and bringing to the boil.
Let the joint gently simmer for an hour with the lid on.
Once an hour is up, turn off the heat and leave to infuse in the pot for half an hour. This is the perfect time to start preparing other side dishes and pre-hating the oven to gas mark 3 (170 degrees).
After letting the meat rest in the broth, move over into an oven roasting dish.
Remove the skin from the joint and score the fat that is left on the joint in a criss-cross pattern.
Season with the salt and pepper, rubbing deep into the grooves.
Pop the ham into the oven for 30 minutes, or until the fat has started to become crisp.
Mix up the bourbon, rosemary and marmalade and spread roughly half over the meat. Place back into the oven and cook for another 20 mins.
Smother the last of the glaze over the meat and baste with a little of the juices in the bottom of the pan.
Put the ham back in the oven and cook for another 30 mins until the glaze is sticky and the ham cooked but moist.