Preheat the oven to 220°C / gas mark 8.
Season the meat with salt and pepper. In a small bowl, mix the herbs with the olive oil and breadcrumbs. Rub both sides of the lamb with the herb mixture.
Using the kitchen string, tie up the lamb leg at 5cm intervals. Place in roasting tin and bake for 20 minutes.
Lower the oven temperature to 190°C / gas mark 5. Add the wine and water or broth to the roasting tin and cook for another 30 to 40 minutes, or until the thickest part of the lamb reaches an internal temperature of 60°C for medium. Take the lamb out of the oven, cover loosely with foil, and let the meat rest for 15 minutes. Slice and serve.