Preheat the oven to 150c.
Spread the vegetables evenly in the tin and add the bay leaf, sprigs of thyme and parsley, and black peppercorns.
Sit the gammon on top of the chopped vegetables and herbs.
Pour in the water so that it comes about two thirds up the side of the tin. Loosely cover with foil. Very carefully transfer the tin to the oven and cook for 1.5hrs. Top Tip : If the water only goes halfway up the joint, you can turn it over half way through.
Remove the roasting tin from the oven (be careful of the hot water and steam as you open the oven door) remove the gammon from the water and discard the water and leave the gammon to cool. Leave the oven on.