The day before you want to make the gala pie, 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 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 ½cm thick. Fold the dough in thirds (like a letter), then repeat this roll and fold again.
Take a standard 1lb loaf tin and place a band of baking parchment across the middle, this will double up as a handle when the pie is baked.
Leave the pastry to cool to room temperature (21C) and then cut off two thirds of the pastry, put the smaller piece to one side and on a floured surface roll out the other piece of pastry, so that it is bigger than the loaf tin.
Place the pastry in the tin and mould it up the sides of the tin and ensure there is enough to join to the lid on the edges.
Pack just under half of the prepared meat into the bottom of the pie, add the eggs end to end in a line so that they touch the pastry at each end.
Pack more meat either side of the eggs and a final layer on top to completely encase the eggs.
Roll out the remaining piece of pastry (at this point reserve a little if you want to decorate the top), cut it to size if necessary and then brush the exposed bits of pastry in the tin with the egg so the lid can be stuck together. Crimp the edges of the pastry together and then cut a hole in the middle of the pie, decorate with holly leaves or any decorations of your choice.
Place the pie in the fridge for 30 mins to firm up, then pre-heat the oven to 180C Fan, brush the pie with egg and bake for 2 hours.
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.
Leave the pie in the tin and pour enough jelly into the pie through the hole in the top and leave to chill overnight before eating. You may find that you need to add the jelly in batches, as it will fill up and then you'll be able to fit more gelatine in the pie.
Leave the pie to cool overnight and then eat it the next day, it's delicious served with English mustard or green tomato chutney.