Place the gammon joint in the slow cooker and position the carrots and onions around it. Add the bay leaves, cinnamon, cloves and peppercorns. Pour in the liquids, cover and cook for 5-6 hours on high setting or 7-8 on low setting.
Remove the ham from the slow cooker and set aside to cool. Discard the solids and save the braising liquid to use in soups if you like (have a taste before using as it may be quite salty).
Carefully remove the rind from the gammon joint, leaving a small layer of the fat intact. Lightly score the fat in a diamond pattern, taking care not to cut too deeply.