Place ham in a roasting tin and press whole cloves into the top at 2.5 to 5cm intervals. Pack the top with a layer of brown sugar. Pour enough water into the bottom of the roasting tin to come to a 2.5cm depth. Cover the tin tightly with foil.
Bake for 4 1/2 to 5 hours in the preheated oven (about 45 minutes per kilo) or until the internal temperature of the ham reaches 72 degrees C. Make sure the meat thermometer is not touching the bone. Let stand for about 20 minutes before carving.