Method

1. For the pastry, sift the flour into a bowl and rub in the lard and butter until the mixture resembles breadcrumbs. Add the salt, baking powder and four tablespoons of cold water and mix to a soft dough. Turn out and knead into a ball. Wrap in cling film and leave to chill in the fridge while you make the filling.

2. Preheat the oven to 180C/350F/Gas 4 (fan 160C).

3. For the filling, mix all the ingredients together in a large bowl.

4. Line a 900g/2lb loaf tin with baking parchment. On a lightly floured surface, roll out two thirds of the pastry to a rectangle large enough to line the tin. Drape into the tin and press up against the sides. Spoon the filling into the tin, pressing down to compress.

5. Roll out three quarters of the remaining pastry to a rectangle large enough to cover the tin. Dampen the edges of the pastry with water and press the pastry lid on top to seal. Trim the edges and crimp using the tines of a fork. Roll out the remaining pastry, along with any trimmings, and use to make a bow to decorate the top, then attach with a little water.

6. Glaze with beaten egg and bake for two hours. Remove from the oven and leave to cool in the tin before turning out.