Start off by washing the oranges. Rubbing them well between your hands under running water is a good way of doing this. Trim off the ends and then place into a large pan with the water. Cover and bring to the boil before lowering the heat and simmering for about 1.5 hours.

Remove from the heat and set the oranges aside to cool in a dish. Do not throw away the water in the pan.

Place a small dish into your freezer for testing the marmalade later and once the oranges have cooled, cut them in half and juice them. Add the juice to the pan with the water and then slice the orange peels very finely and add to the pan as well.

Add the sugar and, stirring well until dissolved, bring the mixture to the boil. Once the marmalade is boiling, reduce the heat a tiny bit so that the marmalade is still boiling, but just not quite so fiercely.

Continue to stir the marmalade every couple of minutes to prevent burning. You will need to boil the marmalade for around 1 hour or so, depending on how dark you like it.

When you think it's ready, preheat your oven to 150 degrees Celsius and wash your Preserving Jars and the lids thoroughly. Place into the preheated oven for about 15 minutes or so and then test some marmalade by dropping it onto the cold plate from the freezer. If it forms a skin after 30 seconds it's ready to go.

Spoon the marmalade into the still quite hot preserving jars, filling right up to about 1cm away from the top, and seal immediately.