Heat the oil for the stuffing in a pan, add the onion and celery and fry over a gentle heat, stirring frequently, for about 10 minutes until softened. Turn into a bowl, add the remaining stuffing ingredients with salt and pepper to taste and mix well together. Set aside.
Ease your fingers between the turkey skin and the breast meat. Push in the softened butter to cover the breast completely. Place the turkey skin side down, season with salt and pepper, then spread with the stuffing. Bring the turkey up and around the stuffing to enclose it, making as neat and compact a shape as possible, and secure with string. Tuck a bay leaf under the string.
Weigh the stuffed turkey to calculate the cooking time (see
Lift the turkey out of the tin, cover tightly with foil and rest in a warm place for 15–20 minutes before serving. Meanwhile, pour off the fat from the roasting tin and use the juices to make gravy (see