Season the flour with salt and pepper on a plate. Coat the lamb shanks with the flour.
Heat the oil in a large flameproof casserole and fry the lamb shanks for 5 minutes until browned on all sides, draining to a plate. Add the onion to the casserole and fry for 5 minutes until softened.
Stir the wine and stock into the casserole and bring to a gentle simmer. Add the orange rind and return the lamb to the pan. Cover and cook in a preheated oven, 160°C (325°F), Gas Mark 3, for 1½ hours.
Spoon the tapenade around the lamb, stirring it into the cooking juices. Return the casserole to the oven for a further 30 minutes or until the lamb is very tender and can be pulled easily from the bone with a fork.
Transfer the casserole to the hob and cook gently, uncovered, to thicken the sauce if very thin. Season to taste with salt and pepper and scatter the artichokes around the shanks. Cook for 5 minutes to heat through. Scatter with basil leaves and serve with ciabatta.