Preheat the oven to 425°F. In a flameproof roasting pan, rub the turkey wings and necks with the olive oil. Season with salt and pepper. Roast for about 45 minutes, until golden brown, stirring halfway through.

Transfer the turkey wings and necks to a large pot. Scrape the pan drippings into a heatproof bowl, cover, and refrigerate (to use for the gravy).

Set the roasting pan over moderate heat and add the wine. Cook, stirring to release the browned bits in the pan, until the wine is reduced by half, about 2 minutes.

Scrape the liquid into the pot and add the celery, onion, carrot, thyme, and 8 quarts of water. Bring to a simmer, skimming off any foam as it rises to the surface. Cook over moderate heat until reduced by half, about 2 hours.

Strain the stock into a large heatproof bowl and cool to room temperature.

In a large saucepan, combine the turkey stock, wine, and shallots; bring to a simmer. Cook over moderate heat, stirring occasionally, until reduced by half, about 45 minutes.

Strain the stock into a large bowl. Wipe out the saucepan.

Melt the butter in the saucepan. Add the flour, and cook over moderate heat, whisking often, until deep golden, 4 to 5 minutes.

Whisk in the strained stock and the reserved turkey pan drippings, and bring to a simmer. Cook over moderately high heat, whisking occasionally, until the gravy is thickened, about 5 minutes.

Stir in the fish sauce and Worcestershire sauce, and season with salt and pepper. Add more fish sauce and Worcestershire sauce to taste. Serve hot.