Preheat the oven to 425 degrees F.
Cut the venison into small steaks and dust with seasoned flour. Heat a little butter in a frying pan and sear the steaks quickly. Put the meat into a 3 to 4-pint pie dish, add the port, lemon juice and stock. Sprinkle with grated nutmeg and thyme, salt and pepper. Lay the butter on top (traditionally it would have been lamb suet), cover with the pastry and glaze with beaten egg. Bake in the oven 15 minutes, Lower the oven temperature to 350 and roast for an additional 1 3/4 hours.