Heat Oil and butter in a large casserole add onions and celery to the pan and fry till softened. Meanwhile mix ground allspice with flour and with spread mixture onto a large plate or place in a large plastic bag. Toss a few pieces of venison at a time (to prevent them becoming soggy) in the flour mixture until lightly coated. Spread the floured venison out on a plate until ready to be cooked. When the onion and celery are soft, remove them from the casserole and set aside. Add the venison pieces in batches and cook until well browned and sealed on all sides. Add cranberries/prunes and the orange rind and juice to the casserole along with the stock and stir well. Return the vegetables and the browned venison. to the casserole and heat until simmering. Cover tightly and reduce heat. Simmer for 45 minutes or until venison is tender, stirring occasionally. Season to taste with little salt and plenty of ground black pepper.