Use gravy browning judiciously, otherwise the dish will become unattractively brown. If you cannot obtain it, substitute with caramel food colouring, Worcestershire sauce, instant coffee granules ...
But as Jamie says: "Good gravy ... it's one of the best time savers. "Tip: make sure you give it another taste before serving up. Some great additions for extra flavour include soy sauce, Marmite ...