1. Preheat the oven to gas mark 4 (350° F or 180° C). Wash and dry the meat. Score the skin with a sharp knife in a diagonal lattice.
2. Heat the walnut oil in a frying pan and brown the meat. First fry the skin to a golden colour and season with salt, pepper and paprika. Then turn the meat just once. Crease an oven proof dish with the butter.
3. Place the meat in the oven proof dish, skin face up. Add the red wine and place in the centre of the oven. Bake for approximately 10 minutes.
4. Heat the Cumberland sauce and port, add the currants and simmer for 3 to 4 minutes. Roast the walnuts in a pan. Slice the meat and arrange it on plates. Pour on the sauce and sprinkle with the walnuts. Potato crisps make an ideal accompaniment.