Also known as mutton pies, these have a very long history. In the middle ages, they were frowned upon by the Scottish church, viewed as luxurious, decadent English-style food. In later centuries, they proved to be convenient and sustaining snacks for working people, who would buy them hot from pie-men or pie-wives in the city streets. The space on top of the pie, created by the raised crust, would sometimes be filled with gravy, beans or mashed potato.
Preheat the oven to 200C/400F/Gas 6 and line a baking tray with baking parchment. Cut four strips of greaseproof paper, about 5cm/2in deep and 25cm/10in long, to wrap around the pies. You’ll also need four pieces of cook’s string to secure the paper.
For the filling, mix all the ingredients together in a bowl and season generously with salt and white pepper. Work the liquid into the meat, divide into four portions and mould into balls. Refrigerate while you make the pastry.
To make the pastry, heat 160ml/5½fl oz of water, salt and lard in a saucepan until just boiling. Meanwhile, put the flour in a mixing bowl. Pour the hot liquid onto the flour and mix together with a spoon. Once cool enough to handle, tip onto a floured surface and knead until you have a smooth dough.
Working as quickly as you can, cut off a quarter of the pastry and set aside. Divide the remaining dough into four equally sized balls. Roll out each ball to an 18cm/7in circle, about 5mm/¼in thick. Roll out the remaining pastry and cut out four circular lids, 10cm/4in in diameter.
Place a ball of filling on each large circle of pastry. Gather the pastry around the meat and bring up the sides to form the shape of a pork pie. Keep stretching the pastry so it comes above the meat by around 2cm/1¾in. Dampen the edges of the pies with water and press the lids on top of the filling. Seal the edges together using your fingers. Wrap a strip of greaseproof paper around each pie and secure with string (to make sure the pie holds its shape when cooking). This is much easier if you have someone to help you.
Put the pies on the baking tray and cut a steam hole in the centre of each. Brush with beaten egg yolk and transfer to the fridge to rest for 30 minutes. Bake for 35-40 minutes, or until golden-brown. Serve hot.