Fold the flap of the joint under if not already done. Lard the upper surface in close rows with thin 1½-in. strips of bacon. Slice the carrots, onion, turnip and celery and place in a saucepan with the salt, bouquet garni, peppercorns and enough stock barely to cover the vegetables. Lay the meat on top, cover with greased paper, put on the lid and cook gently for 2 hr., adding more stock when necessary. Heat some dripping in a baking-tin, put the meat in, baste well and bake in a moderate oven (350° F., Gas 4) for ½ hr., basting after 15 min. Have ready a brown roux made from the 1 oz. fat and flour, add ¾ pt. of stock from the saucepan and stir until boiling. Then simmer for 5 min. and season to taste. Serve the meat on a hot dish and serve the sauce separately.