Heat oven to 180C/160C fan/ gas 6. Put the ham into a large roasting tin, then tip in 500ml water. Cover the whole thing loosely with greaseproof paper, then cover with a large sheet of foil, scrunching and sealing it around the edge of the tin. Make sure you leave some room around the ham. Put it in the oven, then turn the heat down to 160C/140C fan/ gas 3 and leave to cook for 5 hrs. Meanwhile, mix the marmalade with the sugar and 50ml water in a small pan, bring to the boil, then set aside and leave to cool.
Take the ham from the oven. Be careful when you lift the foil as there will be a good amount of steam, which can burn. Once the ham has cooled just a little, remove the rind by gently prising the skin from the fat and lifting it away. Try to keep as much fat on the leg as you can as this will keep the ham moist as it roasts. Drain off most of the liquid (this is very good ham stock – keep it and use it for soup), leaving a little in the tin. Turn the oven up to 200C/180C fan/gas 6.
Score lines into the fat with a knife to make large diamond shapes, with the lines about 4cm apart. Brush a third of the marmalade glaze over the joint, really pushing it into the creases and cuts. Now stud the ham with the cloves by poking a clove into the corner of each diamond.
Put a trivet into the roasting tin (if you don’t have one, a few halved carrots will do), then sit the ham on top. Roast the ham, uncovered, for 45-50 mins, brushing with the remaining glaze a few times during cooking, until caramelised and delicious. Carve hot or cold.
I always recommend cooking ham this way – not only does it give the most succulent result but also most people don’t have a pot big enough to boil a ham on the hob. Most raw hams don’t need to be soaked these days, but check with your butcher to be sure. Serve with good-quality piccalilli.