Preheat the slow cooker if necessary; see the manufacturer's instructions. Heat the oil in a large frying pan, add the lamb and fry until browned on both sides. Scoop out of the pan with a slotted spoon and transfer to a plate.
Add the onion to the pan and fry for 5 minutes or until softened. Add the carrots, swede and parsnips and cook for 1–2 minutes, then stir in the flour. Add the potatoes, stock, rosemary and plenty of salt and pepper and bring to the boil, stirring.
Pour into the slow cooker pot, add the lamb and press below the surface of the liquid. Cover with the lid and cook on high for 6–7 hours or until the lamb is falling off the bones and the potatoes are tender.
Spoon into shallow bowls, removing the lamb bones if liked, and sprinkle with the chopped chives and rosemary. Serve with a spoon and fork and crusty bread.