Place the potatoes and water to cover in a large pot over high heat. Boil for 15 minutes. Meanwhile, brown the ground beef in a large skillet over medium high heat; drain excess fat.
To the ground beef, add the tomato sauce, parsley, Worcestershire sauce to taste, salt, ground black pepper and green beans. In a separate small bowl, mix the flour with the 3 tablespoons water and stir into the beef mixture.
Stir all together well. Drain the potatoes, mash and spread over the beef mixture Place 2 to 3 vent holes through the mashed potatoes.
Bake at 350 degrees F (175 degrees C) for 25 minutes. Brush the milk over the potatoes for the last 5 minutes of baking.