Baked Potato with milk

1 lb bacon 1 cup celery , chopped 1/2 onion , chopped 1/2 cup flour 4 lbs baking potatoes , baked until done, peeled and coursely chopped 8 cups chicken stock[...]

1/3 cup margarine 1/2 medium onion (pureed or diced) 2 tablespoons flour 4 large potatoes , peeled and cubed 4 cups milk 1 (14 1/2 ounce) can chicken broth[...]