Melt 150g butter in a saucepan and add orange and lemon juices. Brush the turkey inside and out with the mixture, reserving some for basting. Sprinkle the turkey well with salt and pepper.
Heat the olive oil in a saucepan over medium heat and saute the onion. Add beef mince and sausage meat and cook until meat is browned. Add rice and stir.
Add chestnuts, 75g butter, chicken stock cube dissolved in water and brandy. Add salt and pepper if necessary and simmer until liquid is absorbed and rice is just cooked. Stuff the turkey with this mixture and tie shut or close with poultry clips.
Put the turkey on a rack in a roasting tin and lightly cover with foil (do not seal completely). Add about 5mm water to the bottom of the tin (top up if it evaporates when cooking). Roast 3-4 hours, regularly basting with the remaining butter mixture. In the last 30 minutes of cooking, increase temperature to 200 degrees C and remove the foil. The turkey should reach a minimum internal temperature of 80 degrees C and be golden brown. Let rest 30 minutes before carving.