Preheat the oven to 160°C-180°C. Mix the flour and paprika in a plastic bag, season with salt and pepper. Add the lamb shanks and toss to coat. Reserve any remaining flour.
Heat a large pan over a moderately high heat, add a little oil. Brown the shanks well on all sides. Remove and place them in a large casserole dish.
Reduce heat in pan and add a little extra oil, the onion and garlic. Cook for 1-2 minutes, stir occasionally. Add the reserved flour, and cook a further minute. Stir in the stock and orange juice and, once a sauce is formed, add the prunes, barley, orange rind and thyme.
Pour over the shanks. Cover the dish tightly with its lid, place in oven. Cook for 2 hours or until shanks are very tender. Turn the shanks occasionally and adjust the heat as it cooks if needed. You may need to add a little beef stock or water if it appears too dry.