Photograph: Dan Jones
Preheat the oven to 200°C, fan 180°C, gas 6. Remove the meat from the sausage skins; discard the skins. Mix the sausagemeat with half the sage. In another bowl, mix the 75g butter with the remaining sage.
Carefully lift the skin away from the turkey breast to loosen it. Smear two-thirds of the sage butter under the skin. Stuff the neck end of the turkey with the sausagemeat stuffing, then tuck the skin under the bird. Place in a roasting tin and shape the crown neatly, smoothing the stuffing.
Smear the remaining sage butter over the crown and arrange the bacon on top. Cover loosely with foil and roast for 1 hour 15 minutes.
Remove the foil and baste the turkey with its juices. Return to the oven, uncovered, for 15-30 minutes or until the juices run clear when a skewer is inserted into the thickest part. Rest on a board or serving platter, covered with foil. If you're cooking roast potatoes in the same oven you can turn the oven up high now.
Meanwhile, make the gravy. Pour off most of the fat from the roasting tin, transfer to the hob and stir in the flour, scraping up the bits from the base. Stir in the wine; bubble for a minute or two, stir in the stock and simmer for 5 minutes. Check the seasoning and strain into a gravy boat. Carve and serve with the gravy.
Get ahead: prepare the turkey, ready to cook, the night before; chill. Bring to room temperature before roasting.
Kitchen secret: if your turkey crown weight is different, calculate the cooking time by allowing 35-40 minutes per kilo; weigh after you’ve stuffed it.