Preheat the oven to 150C/130C Fan/Gas 2. Put the gammon in a saucepan that fits snugly. Pour in the orange juice – if the juice doesn’t cover the ham, top up with water until it’s submerged.
For the glaze, mix the honey and mustard together and brush half of it evenly over the gammon, including one side of the joint. Roast in the centre of the oven for 10 minutes, then take the joint ...