Place the gammon in a large pan, cover with cold water and bring to the boil.
Once it starts boiling drain the water and cover the ham with water again.
Peel and chop the onion and carrot, chop the celery and add to the water with the peppercorns
Bring to the boil and simmer for 2½ hours.
Remove the ham from the pan. It can be left to cool and put into the fridge to cook the next day or you can bake it straight away.
Preheat the oven to 200C, Gas Mark 4.
Place the ham on some tin foil and pour over some ginger ale wrap it up and place it in the oven for ½ hour.
Mix together the marmalade and brown sugar.
Remove the ham from the oven and coat in the glaze.
Wrap it back up and cook for 45 minutes, basting with more glaze at regular intervals.