Preheat the oven to 200 C/400 F/180 FAN/Gas 6.
Pat the duck breast dry with kitchen paper and score the fat diagonally, both ways.
Season both sides with salt and pepper.
Put the duck breast skin down in a cold frying pan and cook over a medium to high heat for t 5 minutes, until the skin is crispy and golden brown.
Turn the fillets over and cook for 1-2 minutes until all sides are brown..
Put the duck in an ovenproof dish then roast for 12 - 15 minutes for medium.
Loosely cover with foil and let it rest in a warm place for 5-10 minutes.
Use a sharp knife to cut the rind from one of the oranges and shred it into thin strips.
Juice the oranges and the lemon.
Put the sugar and vinegar in a saucepan over a medium heat.
Stir while the sugar dissolves until the mixture turn dark brown.
Add the brandy, wine and juice and bring to a simmer for 5 minutes
Add the orange shreds to the pan.
Mix the cornflour with the water and stir into the sauce.
Bring to the boil and cook for 3 minutes until the mixture is thickened and glossy.Check the seasoning.
Slice the duck before serving with the sauce on the side.