Make the stuffing by heating the butter in a pan, add the bacon, onion and celery and cook over a medium heat for 4 - 5 minutes. Turn into a bowl and allow to cool. Add the rest of the ingredients and mix together. Wipe the inside of the turkey and stuff the neck end, folding the neck skin over and securing with a metal skewer. Extra stuffing can be spooned into a small greased loaf tin, covered with foil and cooked for 40 minutes in the oven at the end of the cooking time for the turkey.
Weigh the turkey and calculate the cooking time, allowing 20 minutes per kg plus 90 minutes. Place the turkey in a roasting tin, brush with half the softened butter, season with salt and pepper and place the bacon rashers over the bird, if using, otherwise, loosely cover with foil. Roast in the oven at 180°C/350°F/Gas Mark 4, basting from time to time. Remove the bacon or foil 30 minutes before the end of cooking, mix the orange rind with the remaining butter and brush over the turkey.
When the turkey is cooked, the juices that run out of the thigh when pierced with a skewer should be clear.
Lift the turkey onto a serving plate and allow to stand for 15 minutes, while making the gravy.
Skim the fat off the juices from the turkey, pour the juices into a saucepan and add the stock. Simmer for 5 minutes.
Blend the cornflour with the orange juice, stir into the pan and stir until boiling. Simmer for 5 minutes. Add the whisky and season if needed and strain into a warmed gravy boat. Serve the extra stuffing sliced with the carved turkey.