Cured joints can be very salty, so it's best to soak this ham fillet overnight in cold water, then drain and cover with fresh water for cooking. The ham fillet can be cooked a day or two before required, then reheated in the oven (with some water for added moisture to help prevent it from drying out) for an hour or so before glazing.
Tip: Use goat's butter in the mash to make it dairy free