Put the orange chunks in a large sterilised preserving jar and pour over the wine. Cover and set in a dark, cool place for two weeks.
Strain the juice into a saucepan and add the sugar. Heat gently, stirring to help the sugar dissolve. Cool, then add the brandy or rum.
Pour through a muslin-lined sieve into a jug. Using a sterilised funnel, pour this into a sterilised bottle(s). Seal with a screw cap or, if you are using a Kilner-style bottle, clamp it closed.
Let the bottle stand for a week in a cool, dark place. It will keep for six months