Preheat the oven to 190c/gas mark 5. Wash the turkey inside and out and dry well with kitchen paper.
Put the orange quarters into the turkey’s cavity. If you are stuffing the turkey, put the stuffing in the neck end, pushing it upwards toward the breast. Don’t pull the neck skin too tightly as the stuffing will expand during cooking. Secure the skin with wooden or metal skewers crossways and tie the turkey legs together at the top of the drumsticks for a good shape.
Weigh the turkey and calculate the cooking time. 18 mins per 450g.
Grease a large roasting tin with some of the butter. Smear the rest over the turkey skin and season well with salt and pepper, then place in the tin.
Loosely cover the foil and roast for the calculated time. Meanwhile, halve the rashers, stretch slightly and wrap around each cocktail sausage.
Baste the turkey every hour. One hour before cooking time ends, remove the foil and drain off the excess fat. Thirty minutes before the end of cooking, put the sausages around the turkey or in a separate lightly-oiled tin, if you have no space.
To check if the turkey is cooked, insert a skewer into the thickest part of the thigh – the juices should run clear. If they are pinkish, cook for 15 minutes more and test again.
Transfer the turkey and sausages to a platter, tightly cover with tin foil and allow to rest for thirty minutes before carving. Serve with vegetables and stuffing balls and garnish with sage and rosemary.