To make the jelly, place the bones, vegetables, bouquet garni and peppercorns in the large saucepan and cover with a litre of water.
Bring to the boil and simmer for at least 1 and a half hours.
Meanwhile, make the pie filling by placing all the ingredients into a large mixing bowl and use your hands to massage everything together evenly. Season with salt and freshly ground black pepper.
Cover with clingfilm and place in the fridge until needed.
To make the pastry place the lard and water in the small saucepan and heat until the lard has melted.
Sift the flour into a large mixing bowl and season with salt and freshly ground black pepper and mix well.
Make a well in the centre of the flour and pour in the hot lard mixture.
Use a wooden spoon to mix in and then use your hands to bring to a dough.
Turn the dough out onto a lightly floured work surface and knead for a few minutes until the dough is very smooth.
Form the dough into a ball, wrap in clingfilm and place in the fridge for 30 minutes.
Rub the pie dolly (jar or container) with oil and wrap in cling film.
Remove the pastry from the fridge and pinch off a quarter of the pastry, wrap in clingfilm and set aside.
Roll the remaining pastry into a ball.
Place the pie dolly into the middle of the pastry ball and press down to flatten the base to about 5mm. Draw the edges of the pastry up around the sides, pressing the pastry from the bottom upwards to about 3mm thick to create the pie casing.
Trim around the top of the pie so that it’s even.
Remove the dolly from the pastry leaving the cling film. Carefully remove the cling film.
Take the meat filling out of the fridge, roll into a ball and carefully place into the pastry case. Bring the pastry up further if necessary so it is the same height as the meat filling.
Roll out the remaining piece of pastry into a circle large enough to cover the pastry case as a lid.
Brush the top edges of the pastry case with some of the beaten egg and place the pastry circle on top.
Pinch the edges of the pastry with your fingers to seal the pie.
Make a hole in the centre of the pastry lid. Make a funnel with a folded piece of kitchen foil and place in the hole ensuring the walls of the funnel are flush to the pastry.
Grease the baking sheet with lard.
Place the pie on the baking sheet and chill in the fridge for 2 hours.
Preheat the oven to 180C/350F/gas 4.
Remove from the fridge and brush the pie all over with the beaten egg.
Place in the oven and bake in for an hour and a half or until the temperature of the meat comes to 74C/165F using a meat thermometer. If the pie starts to darken in colour too much during the cooking time place a sheet of kitchen foil over the top.
Remove from the oven and allow to cool to room temperature.
Place the gelatine leaves in a bowl of cold water and leave to soak for at least 10 minutes.
Strain 500ml of pork stock into a clean saucepan and heat up to boiling. Take off the heat.
Remove the gelatine leaves from the water and squeeze out any excess moisture. Add to the hot stock and stir until the leaves have dissolved. Pour into a jug.
When both the pie and the stock have cooled to room temperature pour the stock into the pie via the central hole.
Chill the pie in the fridge until the jelly is set - at least 2 hours.
