To get the turkey ready for roasting, preheat oven to 350°F (175°C). Rub turkey with half of the thyme and rosemary, all of the olive oil,salt, allspice and garlic.
To make the mirepoix for the turkey, combine the mirepoix ingredients in a mixing bowl.Mirepoix for Turkey 2 carrots (peeled and diced) 2 yellow onions (diced) 2 whole bunches of celery (diced) Stuff half the mirepoix and the rest of the thyme and rosemary into the cavity of the turkey. Place the other half of the mirepoix in an ungreased roasting pan. Place the turkey in the pan, breast side up, over the mirepoix. Bake for about 3 hours or until the temperature of the breast reaches 170°F (77°C), the thigh reaches 180°F (82°C) and the stuffing reaches 165°F (74°C). Let turkey cool for approximately 30 minutes before carving.
To make the gravy, in a large cooking pan over high heat, caramelize the turkey bones, drumsticks, giblets, leeks and mirepoix with the butter. After they are seared off, mix in the tomato paste and the sugar. To caramelize, bake for 30 minutes at 350°F (175°C) in the oven. Return the pan to the stove. Add the sherry, white wine, bouquet garni, thyme and sage, and cook to reduce to a syrup consistency. Add the turkey stock; heat to boiling. Reduce to simmering; cook about 20 minutes or until turkey drumsticks and giblets are cooked through.
Remove and strain the stock. Let cool and slowly stir in the cubes of butter. Turkey roasting juices can be added to the gravy before seasoning and thickening. Add salt and peppercorns to taste.