Place the turkey giblets, water, allspice berries, black peppercorns, bay leaves, cinnamon stick, celery, carrots, onion, salt and clementine zest and juice into a large saucepan and bring the mixture to a boil. Cover the saucepan with a lid and reduce the heat so that the mixture simmers gently. Cook for 2 hours.
Remove the saucepan from the heat and strain the gravy stock through a sieve into a clean large measuring jug. This should give you about 1 liter of stock.
When you are ready to make the gravy, remove the cooked turkey from the roasting pan and let it rest on a clean carving board. Pour the turkey juices from the roasting tin into a clean saucepan. Place the flour into a small bowl. Add a few tablespoons of the gravy stock and mix well with a handheld whisk. Add the flour and stock mixture to the saucepan and mix well over medium heat until the ingredients have combined.
Gradually add the stock and honey to the saucepan and mix well. Let the gravy bubble away until it thickens and the floury taste disappears. Pour into a jug or sauceboat and serve with cooked Nigella's Spiced and Super-Juicy Roast Turkey.
For the turkey:
Place the water into your largest cooking pot or bucket/plastic bin and add all the turkey ingredients, stirring to dissolve the salt, sugar, syrup and honey. (Squeeze the juice of the orange quarters into the brine before you chuck in the pieces.)
Untie and remove any string or trussing attached to the turkey, shake it free and add it to the liquid. Add more water if the turkey is not completely submerged. Keep the mixture in a cold place, even outside overnight or for up 1 or 2 days before you cook it, remembering to take it out of its liquid (and wiping it dry with kitchen-towel) a good 40 or 50 minutes before it has to go into the oven. Turkeys - indeed this is the case for all meat - should be at room temperature before being put in the preheated oven. If you're at all concerned - the cold water in the brine will really chill this bird - then just cook the turkey for longer than its actual weight requires.
For the basting glaze:
Place the butter and syrup into a saucepan and cook over a low heat, while stirring, until the ingredients have melted and combined.
Brush the turkey with the glaze before roasting, and baste periodically throughout the roasting time.
Preheat the oven to 425 degrees F.
Cook the turkey for 30 minutes at this relatively high temperature, then turn the oven down to 350 degrees F and continue cooking, turning the oven back up to 425 degrees F for the final15 minutes or so if you want to give a browning boost to the skin. For a 9 to 11-pound turkey, allow 2 1/2 to 3-hours in total. But remember that ovens vary enormously, so just check by piercing the flesh between leg and body with a small sharp knife: when the juices run clear, the turkey is cooked.
Just as it's crucial to let the turkey come to room temperature before it goes in to the oven, so it's important to let it stand out of the oven for a good 20 minutes before you actually carve it.