Ingredients
2lb Seville (bitter) oranges
2 2/3 pints water
4lbs demerara sugar

Method

Wash the oranges, put them in a large pan, cover with water, bring to a boil, and then simmer for 2 hours. Turn off the heat to allow it to cool, saving the water.
Lift out the fruit and cut up the oranges as finely as you wish, saving the seeds separately.
Boil the seeds in water for 5 minutes, then remove them.
Add the chopped fruit and the sugar, bring to the boil, and allow to boil until the temperature reaches 220 degrees F on your jam thermometer. Alternatively, have a saucer in your fridge. When the marmalade is beginning to thicken, put a drop on the cold saucer, and leave in the fridge for a couple of minutes. When the surface wrinkles when you have gently pushed it from the side with your finger, then it is ready for bottling.
Have the jars warmed in the oven, fill using a ladle and then screw the top on and leave on a surface till cooled before placing in your store cupboard. The marmalade sets over 24 hours.