Preheat the oven to 180ºC / gas mark 4. Heat the oil in a large frying pan and fry the beef until browned. Stir in the flour and cook for 1 minute, add the stock and bring to the boil. Stir in the carrot and potatoes. Transfer to an ovenproof casserole dish, cover and bake for 1 hour.
Add the leek and bake for a further 1 hour. Add the greens and cook for 10 minutes. Stir in the rosemary, season to taste and serve.