Preheat to 180°C / 350°F. Prepare the lamb by trimming any excess fat.
In a small bowl, mix the honey, olive oil, Dijon mustard, wholegrain mustard, garlic, lemon juice, salt and pepper.
Spread the chopped potatoes across the base of a large roasting dish.
Brush the entire leg of lamb with the glaze and place on top of the potatoes. Pour the chicken stock around the potatoes.
Loosely cover the lamb with foil (ensure it isn’t touching), and roast for 65–70 minutes.
Remove the foil, baste with the remaining glaze, and gently turn or stir the potatoes. Continue to roast uncovered for a further 30–35 minutes, or until the lamb reaches an internal temperature of 130°F / 53°C for perfectly pink meat.
Remove from the oven and let the lamb rest for 30 minutes, loosely covered with foil. The internal temperature will rise slightly.
Remove the lamb and potatoes from the pan and set aside. Place the baking tray over a burner on medium heat and sprinkle the traditional gravy mix into the pan with the remaining juices and whisk well. Add a little more stock or water if necessary until the gravy thickens.
Carve the lamb and serve with a side of potatoes and the gravy.