Pour the sugar into a large preserving pan or saucepan, add the vinegar and place on the hob over a low heat, stirring frequently, to dissolve the sugar. Once dissolved, turn up the heat slightly and boil for about 20 minutes, until the mixture is syrupy and clear.
Meanwhile, cut chillies in half and remove the seeds (it’s worth using plastic gloves for this bit). Pulse in a blender until finely chopped. Put aside then repeat with the peppers.
Once the sugar and vinegar is ready, add the chillies and peppers, bring to the boil again over a medium heat and then boil for 3 minutes.
Remove from the heat and leave to cool for 15 minutes. Then stir in the pectin and keep stirring until the mixture starts to thicken and the chillies are suspended in the sugar mix. Using a funnel, pour into clean, sterilised jars. If the chillies rise to the top of the jelly then pour back into the pan and stir over a low heat until they are suspended. Once the jelly is jarred up, leave to cool, then seal tightly.