Wash 650g limes and 2 lemons. Peel the zest of limes with a vegetable peeler and finely shred. Place in the preserving pan.
Halve all the fruit and squeeze the juice. Pour the juice into a large jug and top up to 2 litres (3¼pts) with cold water. Pour the juice into the preserving pan.
Line a bowl with a square of muslin. Cut the fruit into smaller chunks and place with any pips into the bowl. Tie up the muslin with a piece of kitchen string and place in the pan.
Cover and leave to soak overnight to help soften the peel.
The next day, slowly bring the pan to the boil, then reduce the heat and simmer gently for 45 minutes to 1 hour until the peel is very soft.
Remove from the heat. Lift out the muslin bag and leave until cool enough to handle then squeeze as much of the juice and pectin as you can out of the bag by pressing between two saucers or by squeezing with your hands. Discard the muslin and its contents
Place a couple of saucers in the freezer ready to do the wrinkle test. Add 1¼kg sugar to the pan and heat gently stirring until the sugar has dissolved.
Bring to a rolling boil skimming off any scum and froth as you go, Boil for about 30-40 minutes or until setting point is reached (105-110℃/ 221-230 °F). Turn off heat, and do the wrinkle test place a few drops on the cold saucer and return to the freezer for a few minutes. If it wrinkles its ready if not boil for another 10 minutes and rest.
Allow the marmalade to stand for 15 minutes and give it one last skim to remove any scum that has formed. Stir then ladle the marmalade into sterilised jars, Cover with a waxed disc, then seal.
Notes
How to sterilise the jars
Wash the jars in warm soapy water and rinse well. Do not dry.
Place the wet jars on a tray, heat the oven to 140℃ (120℃ fan)/275°F /gas 1 and put the jars in the oven to dry completely.
Sterilise the lids (and rubber rings if using Kilner style jars) in a pan of boiling water for 5 minutes.
I always sterilise one or two more jars than I think I will need, to ensure I have enough.StoreIn a cool dark place, the marmalade will keep for at least one jear unopened. Once opened use within 3 months.Nutrition information is per jar based on 5 jars and calculated usingan online nutrition database - is approximate and is meant as a guideline only.