Peel and slice the potatoes and apples. Cut the bacon into small pieces. In an ovenware dish, put a layer of potato slices, then a layer of bacon and a layer of apples. Season the layers with salt and pepper. Repeat the layers until the dish is full, and then moisten with a little stock. Cover with pastry. Bake at 400°F, 200°C, gas mark 6 for one hour. This pie was often eaten at harvest suppers. Neck of lamb can be substituted for the bacon.