1) Place the sausages in a baking tray and roast for 20 minutes. 2) Meanwhile, heat the oil in a flame-proof casserole and brown the shallots on all sides. Stir in the garlic, bacon and celery, cook 5 minutes more. 3) Add the sausages to the casserole with the tomatoes, wine, stock and beans. 4) Bring to the boil and simmer gently for 10 minutes. 5) Stir in the blended cornflour, most of the thyme and seasoning to taste. 6) Cook for a further 5 minutes and serve sprinkled with the remaining thyme.