To make the glaze, place a small saucepan over low heat and add the Christmas Cake and Pudding Spice, orange marmalade, brown sugar, Dijon mustard, orange juice, and sweet chilli sauce to it. Mix well and keep stirring until the marmalade has dissolved and the mix is well combined. Set aside.
To prepare the ham, remove its rind by cutting around the ham hock using a small, sharp knife. Run your fingers under the rind, then gently peel it back from the end opposite the hock and discard.
With the same knife, score the fat in a crisscross fashion. Stud the center of each diamond with a clove.
Transfer the ham onto a wire rack suspended over a large, deep baking tray. Add the water and orange juice to the bottom of the tray, this will prevent the glaze from burning as it drips down the ham during the roasting and basting process.
Brush the ham with the glaze prepared earlier, making sure the ham is well coated.
Place it into the preheated oven and bake for 1 ½ hours, basting with glaze every 10-15 minutes until golden and caramelised.
To serve, cut the ham into thin slices. Serve warm or cold.