Preheat the oven to 170°C/150°C fan oven/Gas Mark 3. Heat the oil and butter in a deep flameproof casserole. Add the guinea fowl in batches and cook until browned on the skin side before turning and browning on the other side. Remove with a slotted spoon and set aside. Add the shallots, bacon, tangerine halves and kumquats to the pan and cook, stirring, until brown. Stir in the ginger and garlic and cook for 1 minute.

Stir in the flour, Madeira and stock. Return the joints to the casserole, then add the cinnamon stick, tangerine juice and redcurrant jelly.

Bring to the boil; cover and cook in the oven for 50 to 60 minutes or until tender. (The cooking time depends on the thickness of the joints, not their weight, so return it to the oven, if necessary.)

Discard the cinnamon stick. Lift the guinea fowl out of the sauce, cover with foil and keep warm. In a small pan, bring the sauce to the boil, add the chestnuts, if using, and bubble for 10 minutes or until reduced by half. Pour over the guinea fowl, to serve. Garnish with the parsley and serve with couscous on the side.