Preheat the slow cooker if necessary; see the manufacturer's instructions. Heat the oil in a large frying pan, add the lamb and fry, turning until browned on all sides. Arrange the potatoes in the base of the slow cooker pot, then put the lamb on top.
Add the onion to the pan and fry until softened, then mix in the garlic. Add the wine, stock, honey, oregano and a little salt and pepper and bring to the boil. Pour over the lamb, then add the lemons and olives, if using.
Cover with the lid and cook on high for 5–7 hours or until the potatoes are tender and the lamb is almost falling off the bone. Spoon into shallow bowls and sprinkle with parsley. Serve with a green salad.