Stir the eggs in a soup plate, and in a second soup plate cut up the oysters moderately fine. Rub the bottom of a chafing dish with anchovy paste. Put in a good sized piece of butter (3 tablespoons) and proceed to cook eggs gently to a creamy scramble. Just as they are turning, throw in the oysters and stir until well blended and cooked through. Season to taste and serve on toast lightly spread with anchovy paste and garnished with watercress or parsley.