Peel the pears. Split the vanilla in half lengthways.
Cut the unpeeled oranges into pieces.
Peel and slice the ginger very thinly.
Bring 1 litre of water to the boil in a flameproof casserole dish with the sugar, oranges, ginger, cinnamon and vanilla.
Place the whole pears in the syrup and cook for 30–40 minutes over low heat, until the pears are just soft.