Add the plums, orange rind and juice and measurement water to a preserving pan. Tie the cinnamon stick and cloves in muslin, then add to the preserving pan. Cover and cook gently for 30 minutes, until the plums are softened.
Pour the sugar into the pan and heat gently, stirring from time to time, until dissolved. Bring to the boil, then boil rapidly until setting point is reached (20–25 minutes). Discard the bag of spices. Skim the jam with a draining spoon or stir in butter, if needed.
Ladle into warm, dry jars, filling to the very top. Cover with screw-top lids, or with waxed discs and cellophane tops secured with elastic bands. Label and leave to cool.
To serve, this jam is delicious in sweet bread rolls with whipped cream, often called Devonshire splits.