Mix the flour on a plate with a little seasoning, then use to coat the chicken joints. Heat the oil in a large shallow flameproof casserole (or frying pan and transfer chicken to a casserole dish later), add the chicken and cook over a high heat until golden on all sides. Lift out on to a plate.
Fry the shallots and bacon until golden, then stir in the garlic and return the chicken to the casserole. Pour over the brandy or cognac and when bubbling flame with a long taper. As soon as the flames subside, pour in the red wine and stock, then mix in the tomato purée and bouquet garni. Season, then cover the casserole and transfer to a preheated oven, 180°C (350°F), Gas Mark 4, and cook for 1¼ hours until tender.
When the chicken is cooked, pour the liquid from the casserole into a saucepan and boil for 5 minutes to reduce and thicken slightly, if liked. Return the liquid to the casserole.
Heat the butter and oil in a frying pan for the croûtons, add the garlic and cook for 1 minute, then add the bread slices in a single layer. Fry on both sides until golden. Serve the coq au vin in shallow bowls topped with the croûtons.