Grate the skin of 1½ oranges and squeeze and strain all the juice. Rub the skin of the bird with seasoned flour, sprinkle with a little orange zest and put half a squeezed orange skin in the bird’s vent. Place in a roasting tin in which the butter has been melted. Spoon a little butter over the bird. Put in a hot oven, 450°F (230°C, Gas Mark 8), and roast for 20 to 25 minutes.
Meanwhile, mix the arrowroot or cornflour with a little orange juice. Mix the remaining orange juice with the well-seasoned brown stock and bring to the boil. Pour a little on to the arrowroot mixture, stirring hard, then pour back into the stock, stirring all the time. Add the remaining zest and stir again. The sauce should be clear and thin and taste strongly of orange. It sets off the wild duck to perfection, as our ancestors well knew.