Preheat the oven to Gas Mark 4, 180°C, (350°F).
Heat a tablespoon of oil in an ovenproof casserole dish big enough to take the chicken. Add in the bacon and brown for 3-4 minutes. Then add the carrot, celery, onion, salt and pepper and cook for another 3-4 minutes. Place the chicken in the casserole and season with salt and pepper. Pour in the stock and cider/water. Bring to a simmer then cover the casserole tightly and place in the oven.
Cook for an hour then remove from the oven. Add the beans to the casserole and stir them through. Add some water if the sauce is drying out. Return the casserole, uncovered, to the oven and cook for another 20 minutes.
Serve the sliced chicken with the sauce, mashed potatoes and roasted vegetables.