Put a large casserole dish on the heat. Pour in the remaining oil, add the lardons and cook until the fat has rendered out and the lardons are crisp. Add the onion and celery to the pan and sweat down until soft. Stir in the apples to soften a little. Add the thyme, sage and the partridges, then pour over the cider and chicken stock and bring to the boil. Cover and transfer to the oven for 25 mins or until the thigh meat is cooked through and will come away from the bone, and the sauce has reduced and thickened. Remove from the oven and serve with the Smoked butter mash (see 'Goes well with').