1. Brine the turkey if you wish. Heat oven to 325°F
2. Pat the turkey dry. Stuff the main cavity with onion, celery, carrot and marjoram. Do not tie the turkey. Slice the skin between leg and breast and spread the leg to provide a more cooking. Place turkey leg side up in a roasting pan with a wire rack. Baste turkey with olive oil. Pour 3 cups of water into the pan.
3. Cook on the lower shelf. Baste regularly. After 3 1/2 hours, pour 1/4 cup of the Port over the turkey. Bake 15 minutes. Repeat basting with Port 3 more times, total of 1 extra hour. Internal temperature should be 170°F for breast, 180F° for thigh. Let rest covered for 15 minutes.
4.  Strain 4 cups of the pan juices into a saucepan, add chicken broth if necessary. Heat to a simmer. Stir the flour into 1/2 cup of the pan juices together in a small bowl until smooth. Whisk into the pan juices, and bring to a boil. Add brandy and simmer 5 minutes. Season with salt and pepper.

NOTES : Serve with Turkey Stuffing.
Can be prepared a couple days ahead of time.