This pie is great because it is so simple and can be made from a tin or good quality ham when you have very little else to feed a fair number of people.
Transfer to a bowl and then add all the other ingredients except the breadcrumbs. Preheat to 200C/400F, and put in a baking sheet.
Roll out the larger disc of pastry to cover the bottom and sides of a 25cm springform tin with a cm of overhang.
Sprinkle the bottom with breadcrumbs, then fill with the mixture.
Roll out the rest of the dough to make a lid.
Fold the overhang over and seal by pressing down with the tines of a fork.
Just before baking glaze the pie with the milk salt egg combo, and stab it here and there with the prongs of a fork to make steam holes.
Bake at 200c/400f for 10 minutes, then turn it sown to 180c/350f and bake for a further 45 minutes. Leave the pie to cool at least 10 minutes, but 25 is better.