Put the gammon in the largest, deepest saucepan you have and pour over enough cold water to cover it by at least 5cm. Add the mustard powder, cloves, sage and bay, then cover and bring to the boil. Simmer for 1 hr 20 mins, skimming off any foam. Turn off the heat and leave to rest, covered, for 1 hr. Carefully remove the ham from the liquid (you can strain and freeze the cooking liquid to use in soups, stews or for cooking dried beans).

While the ham is cooking, make the glaze. Tip the wholegrain and Dijon mustards, sugar, apple juice, cider and vinegar into a saucepan and bring to a simmer. Cook over a medium heat until the sugar has dissolved, then turn up the heat and bubble for 15-20 mins until the mixture is reduced and syrupy.

Heat the oven to 200C/180C fan/gas 6. Remove any rind from the ham, then score the fat in a criss- cross pattern using a sharp knife. Put in a roasting tin, fat-side up, then brush over the English mustard. Halve the shallots and add to the tin around the ham along with a few more bay leaves, if using. Pour half the glaze over the ham and roast for 30-40 mins, basting every 10 mins using the remaining glaze, until sticky and cooked through. Remove and rest the ham for 5 mins before lifting onto a serving board. Surround with the sticky shallots and bay for a festive garnish, if you like, and more mustard on the side.