Put 50g of the gammon, chopped into small pieces, into a food processor with the sage, pepper, mace and ginger. Add the cold water and blitz this to a smooth paste, then put it into a bowl with the pork chops and remaining gammon, both cut into 1cm cubes and stir well. Chill the filling for at least four hours, preferably overnight.
Rub the butter into the flour until the mixture resembles breadcrumbs. Place the lard and water in a saucepan and heat gently until the lard has melted and the mixture is hot but not boiling.
Add the salt, stir until it dissolves, then pour this over the flour and mix quickly into a dough. Work it with a knife to begin with, then as soon as it is cool enough to get your hands in, knead the dough well with your fingers until it is mixed evenly and formed into a ball.
Press the dough out onto a plate, cover with paper or clingfilm and leave until barely warm (about 24-26C).
Lightly flour the work surface and roll the dough out to about 1/2cm thick. Fold the dough in thirds (like a letter), then repeat this roll and fold again.
Leave the dough to cool to room temperature (21C),
To shape each pie use clean jam jars, wrap them in clingfilm. Roll the pastry out to about 1cm thick and cut out a circle larger than the jars.
Turn the jars upside down drape the pastry over the jars, press the dough against the sides of the jar with your fingers working it to remove any pleats from the pastry, stretch to about 5cm in length.
Repeat with another jar until you have 6 pies.
Place the pie moulds in the fridge for about 5 minutes. Remove them from the fridge and carefully prise the pastry off the jars using a blunt butter knife.
Pack the pies with the filling, then roll out the trimmings to make a lid. Brush water around the inside of the rim of the pastry shell, then lay the lid in place and press it down so that it fits tightly against the filling. Pinch it together firmly with your fingers.
Wrap some strips of non-stick baking parchment around the middle of the pie and tie snugly with string, this will stop the pie bulging.
To finish brush the lid and lip with a little beaten egg and cut a hole in the centre of the lid, make sure it's the size of a fingertip.
Repeat with the other pies.
Chill the pies for 30 minutes heat the oven to 180C and bake on a foil lined tray for 1 1/2 hours, or until the centre of the pie reaches 75C. Let the pies cool for 30 minutes, then make the jelly by crumbling the stock cubes into the boiling water in a jug and stirring well.
Sprinkle the powdered gelatine into the warm water, stirring until dissolved (or cut the leaf gelatine into small pieces and soak in the warm water until soft). Stir this in with the stock and cool slightly. Pour enough jelly into each pie through the hole in the top and leave to chill overnight before eating.
The pies can be quite fragile when still warm, so it is best to leave them on the tray they were cooked on and fill them with the jelly and leave them there overnight.