Pour the collected Beef Roasting Pan Drippings into a saucepan and skim off excess fat, leaving about 2–3 tablespoons of brown juices and fond for flavor.
Place the pan over medium heat and sprinkle in the Plain Flour, whisking constantly to form a smooth paste; cook for 1–2 minutes until the raw flour taste has cooked out and the mixture turns a light golden color.
Gradually whisk in warm Beef Stock, adding a little at a time and stirring vigorously to avoid lumps; once incorporated, add the rest of the stock and bring the mixture to a gentle simmer.
Simmer the gravy for 5–10 minutes, stirring occasionally, until it has thickened to a consistency that coats the back of a spoon—add extra stock or a splash of water if it becomes too thick.
Stir in a splash of Worcestershire Sauce and season to taste with Salt and freshly ground Black Pepper; taste and adjust seasoning or acidity as needed.
For an extra-smooth finish, strain the gravy through a fine-mesh sieve into a serving jug, pressing on the solids to extract all the flavor, then keep warm until ready to serve.
