Place finely-chopped bacon in a pan and fry gently for two minutes. Add chopped celery and grated onion and fry gently for five minutes. Cool. Sift together the flour, salt and pepper and rub in the dripping until the mixture resembles fine breadcrumbs. Stir bacon mixture into flour with the parsley. Beat together the milk and the egg and stir into the flour. Knead very lightly on a floured surface, shape into a rectangle and place in a greased 2-lb loaf tin. Bake at 375°F, 190°C, gas mark 5 for one hour. Remove from the tin and serve sliced, warm or cold, with butter.